DOUBLE cannot convert the input expression into a double array

I try to plote :

C1=100e-12; C2=100e-12; R1=2.2e3; L=150e-9; V1=6; syms vC1(t)
DvC1 = diff(vC1); D2vC1=diff(vC1,2);
vC1(t) = dsolve((V1 - L* C1*diff(vC1,2) - vC1)/R1 + C2*( - L* C1*diff(vC1, 3) - diff(vC1)) == C1*diff(vC1), vC1(0)==0, DvC1(0)==0, D2vC1(0)==0  );

iL=C1*diff(vC1); vR1=R1*(iL-C2*diff(vR1)); vOut = vC1 + vR1;
x=0:1e-5:10*R1*C1; 
plot(x, double(subs(vOut,t,x)), 'r', x, double(subs(vC1,t,x)), 'b', x, double(subs(vR1,t,x)), 'g')

An error is: Error using mupadmex Error in MuPAD command: DOUBLE cannot convert the input expression into a double array.

If the input expression contains a symbolic variable, use the VPA function instead.

Error in sym/double (line 827) Xstr = mupadmex('symobj::double', S.s, 0);