No direct postings error

Hi All,

I need your help in this issue

While doing some testing, I am trying to post an service activity to the network.  when filling service specifications i am not able to give cost element.

I am getting an error "No direct postings can be made to G/L acct. 43601100 in CoCode 1000". Please explain what does it means.

My question is, is there any specification in GL accounts ? only that has to be used in project systems?

Rergards,

Wasim