[CST] Maximum simulation time reached, solver stopped.

I am trying to simulate an antenna at 0.3 THz. I m using a wave-guide port to excite it. Its a simple patch antenna structure with SiO2 as substrates and Drude model Silver as conductors. I came across the following error.
"Maximum simulation time reached, solver stopped."

I know this error can be resolved by increasing the "Number of pulses" from 20 to a higher number. I have increased it till 1000, but still the error appears. Any other solution to this error.

Awaiting replies,

Regards