CFL error when using Modified and Multi-Scale Kain-Fritsch schemes on WRFV4.1.5

I am running a 2 domain cumulus parameterization study. The outer and inner domains are 50 km and 10 km. I have successfully used a few different cumulus schemes, including Old Kain-Fritsch (CU99) and Kain-Fritsch cumulus potential (CU10) schemes. The error is occurring in d02.

Unfortunately adjusting the time step did not solve the problem. The default time step is 180, but I have also tried running wrf using a time step of 300, 120, 90 and 60. Any suggestions on what else I can try?

I have attached my namelist.input (that initialises the Multi-scale Kain Fritsch scheme) and the rsl.error.* log files.

The error message indicates that TBOUND exceeds table limit. Apparently something is wrong in the physics.
I have a few suggestions about the namelist settings:
(1) For dx=50km, you may set time step = 300. As a conservative option, you may try 240
(2) please turn on w_damping
(3) please set epssm =0.5, 0.5 just in case the topography is steep

I am not sure whether the above options can make this case work. if it still failed, you need to look at the wrfout saved right before the model crashed. Please look at all variables and find the first grid point/first time step something goes wrong, then trace back to figure out the reason.

Thanks. Hopefully the suggested adjustments work.