Count of Characters in Paragraph field

Hi All,

     I have a Paragraph field in the grid, which i have limited to 500 char, but i want to show the count of characters below the paragraph, for that am using Instructions,still with no luck,

    Can anyone please help me on this,

a!paragraphField(
                              value: fv!item.comments,
                              saveInto: fv!item.comments,
                              height: "SHORT",
                              instructions: "Number of characters " & len(fv!item.comments) & "/500",
    refreshAfter: "KEYPRESS",
                              disabled: if(
                                local!accessoftheGroups = cons!CMP_GROUP_ACCESS_VALUES[2],
                                true,
                                false
                              ),
                              validations: if(
                                len(fv!item.comments) <= 500,
                                "",
                                "500 characters maximum."
                              )
                            )

    Thanks in advance

Warm Regards

Vineeth