Mysterious error with area load

[iodadi]

When I assign area load Uniform to frame (SAP2000 v.10.0.1)I receive the following error message:
"Error in creating analysis model".
Why?
Thanks a lot,
Davide

 

[DENSAL55]

when can not assign area load to frame, but we can assign area load to area object.

 

[iodadi]

But the SAP2000 v.10 could permit it, I think....
It's that the problem...