Incompleteness check on Header text in customs declaration

We have a requirement for incompleteness check on header text in customs declaration

Users type information in "Internal Note" (Text ID 0001) in header text of customs declaration which is then printed on the export packing list. We want to make this a mandatory entry and if its missing, then it should show in the incompleteness check for that message.

I tried creating a field in "field definition" as below and assigning it to the check procedure.

Table Name          HD_TXT

Field Name           ITVSY

Qualifier Value

Tab Page              SLL_TAB_TXT_HDR

Now the issue is even if I type some text in internal note, I still get the error to "Item does not exist". I have tried changing the Field Name value (TDID, TDSPRAS, TDSPRAS_ISO, TDOBJECT, TDOBNAME) but it doesn't help. Any suggestions as to how I can achieve this.