Waveguide port in CST

I could not find a solution in this forum in previous discussions.

The error i get when putting wave guide port for Grounded CPW structure is this:
'Waveguide for port number 1 is too short. The waveguide must be homogeneous for at least three mesh planes along propagation direction.'
I introduced subgridding and increased mesh density, Waveguide port is +3(w) and -3(w)
where w = width of feed line + gap from ground on both sides.
I increased port size as well.

Now this is the notification
'The first three mesh cells within the region of port 2 seem to be inhomgeneously filled (at least slightly). Matrix coefficient calculation continues creating a homogeneously filled port region for the simulation setup.'

Error: Port 1 is inhomogeneously filled within the first 3 mesh cells. Cannot start solver.

Help?!

Post a pic of your sim with mesh cell view! it's easier to understand your problem. Use the mesh view, the first three mesh cells should contain only ONE material!

Thanks for this.
The waveguide port is perpendicular to y axis so my mesh cell view should be Normal to it or do it upload X normal and Z normal?

Here is the Z plane normal view. The mesh size is not uniform along port length and how do I make it only ONE material?

I think the waveguide is too large for your structure, more details can be found in the manual. Your problem are the vias near to the edge. You can further increase the mesh density or extend your cpwg in the -y direction and place a reference plane at your current waveguide position.