The field (of type Editable Text) that will contain the default entry string MUST be DITL item #3.
A second field of editable text MUST be DITL item #4; a Checkbox MUST be DITL item #5.
Follow this outline when constructing the DITL resource:
item #1: OK button (the default)
item #2: Cancel button
item #3: Editable Text field (to contain default entry string)
item #4: Editable Text field (if you want one)*
item #5: Checkbox (if you want one)*
remaining items: Static Text fields, icons, and PICT's
* if you only want one field of Editable Text, it's okay to have item #4 be an icon, static text, PICT, etc. The same goes for item #5, if you don't want a Checkbox.
The ONLY items that are to be ENABLED are buttons, your checkbox (if you have one), and Editable Text fields.