Import a file using a field on a form

[Taz]

I am using Access 2003. I created a form for a user to enter the path and
filename for import. I then added a button that runs a macro to transfer the
text file. In the file name in the macro I have
forms!frmImportData!filename. It is not working. Is it possible to import a
file this way, and if so how do I do it? The filename will change each time
it is imported (a monthly run). I really don't want the user to have to open
the macro and key in the new filename each time. I'm trying to make it as
seamless as possible. TIA.