R help - Sep 2013 - ConstrOptim Function (Related to Constraint Matrix/ui/ci error)

Hello All,
I am stuck in the following problem.

Cexpt=c(0,25,50,100,150,300,250,125,40)
t=c(0,0.2,0.4,0.6,1,4,8,12,24)
theta0= vector of 6 parms (My initial parameter)

A=Constraint matrix (hopefully 6*6)
B= Constraint vector of length 6)
Cfit=function(t,theta){
           J(t)=function(theta,t)
           Cfit=function(J(t),constant)
         return(Cfit)   }

loss=function(theta,t,Cexpt) { sum(Cexpt- Cfit(t,theta))^2}

Final=constrOptim(theta0,loss,t,Cexpt,NULL,A,B)

When i try to fit it gives me error

ERROR IN UI%*% THETA : MATRIX/VECTOR/COMPLEX ARGUEMENTS REQUIRED OR
SOMETHING...

thank you all.

M
J

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