hbt simulation

Dear all,
When I place 3 HBT in parallel for output stage, the loadpull simulation is well done.
However, when I place 4 HBT in parallel, the loadpull simulation is terminated duo to error.
Then error information is follow:
Error detected by hpeesofsim druing HB analysis "HB1", No convergence ~~~~~~~~~~~
Does anybody can tell me the solution? Thanks.
The Win-foundry GaAs HBT process is used in this design.

Added after 11 minutes:

In addtion, The simulation is peformed in ADS

very strange error , try to modify the solver options
and actve krylov

check the attached pic

Have you checked the stability ?

u mean the stability factor ?

khouly

Yes, stability factor might be changed and therefore HB doesn't converge..
It can oscillate..