This is an error that I am not aware of. When you say "Checking" - how are you checking the worksheets? Could you share the version of Desktop and version of Tableau Server that you are utilizing? This may best be handled by creating a ticket for the support team at http://support.tableau.com but please share any solution found here to assist other users.
No worries. I have recreated the report from scratch and is now working. Not sure what the problem was.