Help about CST MWS error simulation

Hi,
Has anyboydy here seen this error? :
"The calculation seems to be unstable, consider reducing the value for the stability factor in the solver specials options or reducing the PBA limit..." (1)
I simulate a planar antenna structure, It worked normally but when I changed some parts on the model, this confused me because sometimes it runs, sometimes it gives (1).
I tryed reducing the PBA too but It s not worked, thanks for giving me some ideas..

hello dear
go through mesh option then global mesh property and increase the mesh cell then simulate .i think ur problem will be removed.

It workd thanks my dear;