v6.11.1 Error when applying pressure to shell element

[PJtree23]

Hi,

I am running ABAQUS v 6.11.1

My model uses exclusively shell elements, to which I want to apply a uniform pressure distribution. When I do this and submit the job, I receive the error:

"Error in job PAB1_31: SURFACE ASSEMBLY__PICKEDSURF181 INCLUDES EDGES. EXCEPT FOR SHELL EDGE LOADING, SURFACES WHICH INCLUDE EDGES CANNOT BE USED WITH *DSLOAD, *DSFLUX, *SFILM, *SRADIATE, *DSFLOW, *SFLOW, *DSECHARGE, *DSECURRENT, *SIMPEDANCE OR *INCIDENT WAVE."

I can't seem to find a work around for this, and I don't even completely understand the error how can a selected surface not include edges???

Please help!

Thanks in advance,

PJ