Blank Fields When Using Runtime

[Gremlin]

We are using Filemaker Version 6 to develop our software. We use the software to autofill forms using data from a database. We have been developing a new version and recently came across a proplem when opening the file using Runtime.

What we started doing was naming fields with either a ~ or a ! in the name. After placing the field into the form, we then run a script that searches the fields and fills them based on these characters. Without going too much into the script just yet, we are running an older version of Filemaker Runtime than what we used to develop the template. (Version 5.0 Runtime vs. Version 6 Developers) Could this be part of the problem? Any other ideas?