Hello Naomi
What is the Excel version of the file?
I have Office Excel 2007 , but i save the file in excel 97-2003 (.XLS)

Also, is msg a custom function?
Yes , is equivalent on VFP to messagebox()
Add BROWSE command right after append to see if append worked (this is just for testing).
Nothing appear and my program crash.

the captionj of error is :
Unhandled exception at 0x003e003f in myapplication.exe: 0xC0000005: Access violation writing location 0x003e003e.

I hope is this is help you.

Many thanks Naomi