Hi. I've upgraded one of two PCs to Office 2013, but the other will continue run Office 2010 for a few months. I edit various files on both PCs and exchange them. It was encouraging to see that all my Word add-ins could be saved upward & downward and exchanged with no issues. But Excel seems a different story. My Personal Macro Workbook, if saved in 2013, gives a missing-DLL error when loaded in 2010. (There's no error if saved in 2010 and loaded in 2013.)

I only barely understand DLLs. How would I go about figuring out what in the PMW is causing this error?

When I view the PMW code in the Visual Basic editor and select each module, for some modules the error displays again, for others it doesn't. (And of course, this is the yelping sort of error, not the kind that highlights a line of code.)  But the code in all the modules is pretty ordinary. What should I look for?

Thanks in advance,

Mark