Question: Gears method | stiff system

Hello, I'm just starting to work with maple I'm working on Enzyme kinetics project and I have no idea how to solve ODE system using GEAR'S or A-stability methods. I'm looking for help.

What is wrong?

> restart;
> Digits := 10;
> dsys := {diff(E(t), t) = -kf*E(t)*S(t)+kr*ES(t)+kcat*ES(t),

                diff(ES(t), t) = kf*E(T)*S(t)-kr*ES(t)-kcat*ES(t),

                diff(P(t), t) = kcat*ES(t),

                diff(S(t), t) = -kf*E(t)*S(t)+kr*ES(t)};
 
kf := 10^6; kr := 10^(-4); kcat := .1;
                       
 isc := {E(0) = 2/e^7, ES(0) = 0, P(0) = 0, S(0) = 5/e^7};
       
 dsol := dsolve({dsys,isc}, numeric, method = gear[polyextr], initstep = 0.15e-1, minstep = 10^(-11), abserr = 0.1e-4, relerr = 0.1e-5);

Error, (in dsolve/numeric/process_input) input system must be an ODE system, got independent variables {T, t}
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