solving nonlinear system of equations

I have a set of non-linear equations that I want to solve. I tried to specify a value for x3 from which I hope Solve function will help me find corresponding solution/solutions. For some reason, the solution solved by matlab contains a different value for x3. Here are the equations

         i=0.1;
         syms x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12 O positive

            [x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12 O] = solve(...
         x3==i,...
         x1==(k11*O+k12*(N-O))*(k1*x5)/(1+k1*x5)/(muD+lamQs),...
         x3==(k11*O+k12*(N-O))/(1+k1*x5)/(muD+lamQl),...
         x5*(lamQar*muD)==k21*O+k22*(N-O)-(k11*O+k12*(N-O))*(k1*x5)/(1+k1*x5),...
         x2==1,x4==1,...
         x7*(k31+lameI)==k3*(x1+x3)*Vcon+k31*x6,...
         x6==k31*x7/(k31+lamiI+muD),...
         x8==k32*x9/(k32+lamiC+muD),...
         O==N*x10/(x10+Kb*x11),...
         x10==k41*x12^4*x6^4/(lam+muD),...
         x11==k42*x12^4*x8^4/(lam+muD),...
         x12*(lamPrg+muD)==(k51*O+k52*(N-O)),...
         x1,x2,x3,x4,x5,x6,x7,x8,x9,x10,x11,x12,O);

Here are the set of parameters if you need to try:

       N=5/0.602;
       k11=7.23*10^-3;   %kQl
       k12=8.871*10^-2;   %kQul
       k21=1.021*10^-2;   %kQal
       k22=1.21*10^-3;    %kQaul
       k1=10^-2;    %kQb
       k3=10^-2;      %ki
       Vcon=1;
       k31=10^-4;  %kTi
       k32=10^-3;  %kTc
       Kb=10^-6;
       lamQs=10^-4;
       lamQl=0.1;
       lamXar=3.851*10^-4;
       lamQar=10^-3;
       lamX=10^-4;
       lameI=10^-6;
       lameC=10^-6;
       lamiI=10^-6;
       lamiC=10^-6;
       lam=10^-6;
       lamPrg=10^-6;
       k51=10^-6;
       k52=10^-5;
       k41=10^-12;    
       k42=10*k41;
       muD=log(2)/(45*60);

The solutions that i got containing x3=62.8957 Thanks, Vu