First check your cost center with KS03, see the tab "control". Actual and plan revenues does have not be flagged. note also the cost center category of your cost center
If they are not flagged check your customising.
Spro>controlling>cost center accounting>master data>cost centers>define cost center categories. for your cost center category of your cost center, remove the flag under ActREV or at PLNREV.
Do your posting again it will solve your problem
Procedure
Assign the account to another cost center or allow cost center SWA255 to again accept revenue postings.
Answer's will be a great help.
~Thanks so much
Lourd