Showing excel data in editable grid

I am trying to show Student Data in editable grid through excel with marks in subjects. there is a field with total marks which is depend on marks from other fields. Problem is i am able to when i change marks of any subject changes get reflect in the MarksObtained field which is the sum of marks of all subjects but when i submit it does not store the changed data in Marksobtained field. it stores the original data which is in excel file.

a!localVariables(
 
a!formLayout(
  label: "Student Details",
  contents: {
    a!sectionLayout(
      contents: {
        a!gridLayout(
          label: "Editable Grid",
          labelPosition: "ABOVE",
          headerCells: {
            a!gridLayoutHeaderCell(label: "RollNumber"),
            a!gridLayoutHeaderCell(label: "FullName"),
            a!gridLayoutHeaderCell(label: "Hindi"),
            a!gridLayoutHeaderCell(label: "English"),
            a!gridLayoutHeaderCell(label: "Maths"),
            a!gridLayoutHeaderCell(label: "Physics"),
            a!gridLayoutHeaderCell(label: "Chemistry"),
            a!gridLayoutHeaderCell(label: "ObtainedMarks"),
            /*a!gridLayoutHeaderCell(label: "TotalMarks"),*/
            a!gridLayoutHeaderCell(label: "Percentage"),
            a!gridLayoutHeaderCell(label: "Result"),
          },
          columnConfigs: {
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            a!gridLayoutColumnConfig(width: "DISTRIBUTE"),
            /*a!gridLayoutColumnConfig(width: "DISTRIBUTE"),*/
          },
          rows: {
            a!forEach(
              items: ri!studentData,
              expression: a!gridRowLayout(
                contents: {
                  a!integerField(
                    value: fv!item.RollNumber,
                    saveInto: fv!item.RollNumber,
                    disabled: true
                  ),
                  a!textField(
                    value: fv!item.FullName,
                    saveinto: fv!item.FullName
                  ),
                  a!integerField(
                    value: fv!item.Hindi,
                    saveInto: fv!item.Hindi,
                    validations: {
                      if(
                        fv!item.Hindi>100,
                        "Marks should be between 0 and 100",
                        if(
                          fv!item.Hindi< 0,
                          "Marks should be between 0 and 100",
                          "")
                    )
                    }
                  ),
                  a!integerField(
                    value: fv!item.English,
                    saveInto: fv!item.English,
                    validations: {
                      if(
                        fv!item.English>100,
                        "Marks should be between 0 and 100",
                        if(
                          fv!item.English< 0,
                          "Marks should be between 0 and 100",
                          "")
                      )
                    }
                  ),
                  a!integerField(
                    value: fv!item.Maths,
                    saveInto: fv!item.Maths,
                    validations: {
                      if(
                        fv!item.Maths>100,
                        "Marks should be between 0 and 100",
                        if(
                          fv!item.Maths< 0,
                          "Marks should be between 0 and 100",
                          "")
                      )
                    }
                  ),
                  a!integerField(
                    value: fv!item.Physics,
                    saveInto: fv!item.Physics,validations: {
                      if(
                        fv!item.Physics>100,
                        "Marks should be between 0 and 100",
                        if(
                          fv!item.Physics< 0,
                          "Marks should be between 0 and 100",
                          "")
                      )
                    }
                  ),
                  a!integerField(
                    value: fv!item.Chemistry,
                    saveInto: fv!item.Chemistry,
                    validations: {
                      if(
                        fv!item.Chemistry>100,
                        "Marks should be between 0 and 100",
                        if(
                          fv!item.Chemistry< 0,
                          "Marks should be between 0 and 100",
                          "")
                      )
                    }
                  ),
                  a!integerField(
                    value: fv!item.Hindi+fv!item.English+fv!item.Maths+fv!item.Chemistry+fv!item.Physics,
                    saveInto:fv!item.MarksObtained,
                    disabled:true
                  ),
                  /*a!integerField(*/
                    /*value: fv!item.TotalMarks,*/
                    /*saveInto: fv!item.TotalMarks*/
                  /*),*/
                  a!floatingPointField(
                    value: (fv!item.Hindi+fv!item.English+fv!item.Maths+fv!item.Chemistry+fv!item.Physics)/fv!item.TotalMarks*100 ,
                    saveInto: fv!item.Percentage,
                    disabled: true
                  ),
                  a!textField(
                    value: If(
                      (fv!item.Hindi+fv!item.English+fv!item.Maths+fv!item.Chemistry+fv!item.Physics)/fv!item.TotalMarks*100 > 33,
                      "Pass",
                      "Fail"
                    ),
                    saveinto: fv!item.Result,
                    disabled: true
                  ),
                }
              )
            )
          },
          selectionSaveInto: {},
          addRowLink: a!dynamicLink(
            label: "Add Student",
            saveInto: {
            }
          ),
          validations: {},
          shadeAlternateRows: true
        )
      }
    )
  },
  buttons: a!buttonLayout(
    primaryButtons: {
      a!buttonWidget(
        label: "Submit",
        saveInto: {
         
        },
        submit: true,
        style: "PRIMARY"
      )
    },
    secondaryButtons: {
      a!buttonWidget(
        label: "Cancel",
        value: true,
        saveInto: ri!cancel,
        submit: true,
        style: "NORMAL",
        validate: false
      )
    }
  )
)
)