If you have too many cell formats you can no longer copy a sheet. It will not give you an error message just won't let you copy the sheet. The issue is not from too many formats but from corrupt styles. There are fixes for the too many cell formats on the web. The easy way to see if this is the problem is on your home tab of your ribbon in the style section there is a drop down. When you select the drop down you see many styles that have very funky names then you have this problem. This typically occurs when you copy from other workbooks into your workbook.