Only first entry taken

So, I have a form for " Document Details", the user can enter as many documents as they want. 

and when they add a document, it should appear in the grid. 

I declared   " local!indexNum" as index , so the user can enter many documents. 

And here is an example code of how i entred data: 

        a!dropdownField(
                  label: "Main Type",
                  labelPosition: "ABOVE",
                  placeholder: "--- Select a Value ---",
                  choiceLabels:local!type['recordType!{ba0dd34e-52a6-4f09-ba3a-dd6885feda5b}SKJ Main Type.fields.{e5eb76e0-4885-44d7-b9c3-263533a5f721}descEn'],
                  choiceValues: local!type['recordType!{ba0dd34e-52a6-4f09-ba3a-dd6885feda5b}SKJ Main Type.fields.{4a008dc7-3ea8-466e-a515-75c5cb965a49}itemCode'],       
                  value:      
                  if(
                    a!isNotNullOrEmpty(local!filled),
                    ri!DocDetails[local!filled].mainType,
                    ri!DocDetails[local!indexNum].mainType
                  ),
                  
               
                  saveInto: {ri!DocDetails[local!indexNum].mainType},

                  searchDisplay: "AUTO",
                  required: true,
                  validations: {}
                )

The thing is that in the grid, and even in the database it only saves the value of the first entry and duplicated it for others: 

But the ri!DocDetails seems to have different values for the 2 different items.  

This is what is in the "Add a document" button : 

        a!buttonWidget(
          label: "Add A Document",
          icon: "plus-circle",
          value: true,
          saveInto:{
              local!clicked,
              a!save(  ri!DocDetails,
              append(ri!DocDetails,local!documentDetails)),
              a!save(local!addDoc,false),
            

            a!save(local!indexNum,local!indexNum + 1),
            a!save(local!addnewdocument,local!addnewdocument + 1)

          },
          style: "LINK"
        )

Tell me if you need to see more of the code .