I am running clm6 with the Compset "I1PtClm60Bgc'' for crop 'rice' .Using one year forcing data, I am getting the below plots (presented for some of the variables). My concern is here, we are getting GPP/CPOOL as 'zero'. What could be the possible reason?

Secondly, when I am trying to spinup the model with the below changes in the xml file
./xmlchange CLM_ACCELERATED_SPINUP="on"
./xmlchange RESUBMIT=3,STOP_N=50,STOP_OPTION=nyears
After spinning up, I am getting the trend plot using the annual mean values of the below variables from the history files.

My question is what could possibly go wrong to get the 'zero' GPP values?

Secondly, when I am trying to spinup the model with the below changes in the xml file
./xmlchange CLM_ACCELERATED_SPINUP="on"
./xmlchange RESUBMIT=3,STOP_N=50,STOP_OPTION=nyears
After spinning up, I am getting the trend plot using the annual mean values of the below variables from the history files.

My question is what could possibly go wrong to get the 'zero' GPP values?