Using fmincon to optimize parameters in an ODE

Hello

I am trying to optimize the following ODE

dV/dT = (p1/B)(exp(-p2/T))(p3-V)

Here, B is a known constant. p1, p2 and p3 are the variables to be optimized.

So I first created function files for the function and the ode as follows.

My objective function is as follows

Initially i used 'lsqnonlin' but it did not give the expected graph. So next, I used the 'fmincon' solver for the optimization. This is the code for the optimization.

V0 = 0.0016; B= 5000;

lb=[1e10,1,0];ub=[1e20,1e20,1];p0=[1e10,100,0.5];

A=[];b=[];Aeq=[];beq=[];nlcon=[];

p_soln=fmincon(@objective,p0,A,b,Aeq,beq,lb,ub,nlcon);

But the results when plotted are not as expected.

Please help me identify what could have gone wrong and suggestions on how to correct it

Thank You!