This generally happens when one workbook is in the .xlsx format, and the other is in .xls. I've had it happen after converting to the latest version, but I suspect if I took the time to close the program and re-open it it would work. My path of least resistance solution is if I can't move sheet X into workbook Y, I move all the sheets of Y into X, and that usually works.

Since you're in Excel 2013, it may be a different incompatibilty, but try that.

Before .xlsx there were 65,536 maximum rows per worksheet. In the current version there are 1,048,576 rows. Thus the error message.

If one of your sheets says it's in Compatibility Mode at the top of the title bar, that's a clue it's in a different format.