Fatal Error : Error while evaluating XC2.X1.Cmain2 capacitor value "Ccap**(1.0+VC1*abs(v(Pos,Neg))+VC2*abs(v(Pos,Neg) )*abs(v(Pos,Neg)))"

I got this fatal error while simulating the common drain amplifer.
please help me in fixing this problem
thanks in advance
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