HI Manimegalai,
Sorry was not able to get back early.
Seems MODEL GUID is not getting populated properly while creating vehicle master into DBM from VMS, hence you are not getting error in DBM .
Do below implement BADI /DBM/BADI_VEH_VMS
Copy code of fall back class /DBM/CL_DEF_IM_VEH_VMS and then implement method
/DBM/IF_VEH_VMS~ENABLE_VMS2DBM here use custom code and populate field EV_MODEL_GUID
Regards
Ganesh