Two compartment model with fixed omega parameters

Dear NMusers, I have tried to find an appropriate base model. I found that two compartment model with fixed Omega of V2 and Omega of Q = 0 (AIC 1860.17) provided smaller AIC than one compartment model (AIC 1921.83) did. >From these findings (no variability on V2 and Q), is it suggesting that one >cpt model could adequately describe the data? I would truly appreciate it if you could give me some suggestions. Kind regards, Waroonrat