aperture coupled patch antenna CST

Hi,

I am trying to simulate a aperture coupled patch antenna, i have many problems in design of waveguide port with CST and when the simulation begins, it always been aborted automatelly with the error:

The current settings will probably lead to a very long simulation time.
You may improve the simulation speed by:
1. check the freq. range and unit settings,
2. extending freq range
3. checking the mesh to avoid very small mesh steps


Anyone could tell me ? Thx.

the attachment is my structure