Fitting Kinetic Parameter using fmincon

Hello. I'm new in Matlab and I really need help in finding kinetic parameters for several chemical reactions. Currently I use ode45 to solve the differential equations and fmincon to find the kinetic parameters (term P in the matlab file). There are 9 reactions that happen simultaneously in one system. Prior from this, I used lscurvefit to fit the data. But, the object function value was quite big.

After running the code, almost all of the 9 reactions is not really fit to the experiment data. I'm struggling in finding the parameter in low objective function because after trying several times I found out that the objective function is no less than 600s. The purpose is obviously to get the objective function as low as possible.

I'm not really sure the code I wrote is corresponding or not. I really hope someone could check my code. Maybe there is suggestion for me to revise the code so I could get better result, better objective function. I've attached the file and I hope someone can help me.

Thank you in advance.

[Star Strider]

I cannot figure out what you’re doing. There are a number of examples in Answers on fitting kinetic differential equations to data, for example Monod Kinetics and curve fitting and Parameter Estimation for a System of Differential Equations. Use those examples as your prototype code.