For some reason I am not able to copy and paste inside a worksheet, among
different sheets.. I can select the cells, press copy, but when moving to the
another sheet the Paste button becomes unavailable.. only for this file. If i
open a new workbook it works properly.. I m not sure if this file is
corrupted or i disabled something. It has a lot of macros in though.Thanks

maybe one of these macro does something on an activate or open event, so
the paste is cleared then.

Look at this possibility