Write a string to a field in a protected word doc

I've coded up a routine that opens up a protected word document containing text entry fields. The problem is when i try to write a string to the entry field. At the moment i move to the bookmark then try to enter text to the current selection.

I get an error saying that the program is trying to write to a protected area of the document.

<vb>
wSourceDoc.GoTo What:=wdGoToBookmark,name:="CompanyProfile"

wApp.Selection.TypeText Text:="my string"
</vb>

I just want to set focus to the field then populate the field with the text string.

any ideas

figured it out, however, my field is limited to 750 chars in the receiving document. When i try to assign a string of length 700 chars i get a message saying 'string too long' error: 4609

i'm doing a trim and even a left(<var>,750) etc and its not helping. If i simply hard-code a value, i.e. "test value" it works ok.

completely puzzled by this, has anyone seen this behaviour before?]

thanks

john