Hi,

I created a .xlsm file where the only bit of code inside is a UDF module to do some simple calculations. I signed it with my digital signature that I've been using for the past 2 years without any issues. However, when a colleague uses the file and duplicates a worksheet in the file, Excel prompts to either discard the signature or close without saving. The worksheet itself does not contain any code. I have temporarily gotten around this by setting my colleague's macro settings to run all macros.

What is the problem causing this? Is there a way to solve it?

Thanks.