Ztosigma error

Hello all!!

I am doing the vertical interpolation to create the ini file and I got this error:

ext_tracers_ini: time index: 1 of total: 120
ext_tracers_ini: horizontal interpolation of seasonal data
ext_tracers_ini: vertical interpolation

min sigma level = -3458.6235 - min z level = -100000
max sigma level = 3499.3143 - max z level = 100

Is it associated with Theta s and Theta b combination?? How can I solve it??

Thanks in advance!