Question: Solving Differential Equation System

Hi everyone 

I want to solvethe following  differential equation system:

> equa1 := c[pa]*L*(diff(T[air](t), t)) = h*(T[sol](t)-T[air](t))+L*L[vap]*(diff(m[v0]-709.2750000*M*exp(1.000000000*10^(-8)*(1.311709131*10^9*T[air](t)-4.892675059*10^11)/T[air](t))/(R*T[air](t)), t));
> equa2 := c[ps]*l*(diff(T[sol](t), t)) = h*(T[air](t)-T[sol](t))-exp(-opt*L*(m[v0]-709.2750000*M*exp(1.000000000*10^(-8)*(1.311709131*10^9*T[air](t)-4.892675059*10^11)/T[air](t))/(R*T[air](t)))/(m[v0]+m[a]))*(k*T[sol](t)+u);
> equa := {equa1, equa2, T[air](t[sat]) = 282.0777392, T[sol](t[sat]) = 268.9808644};
> dsolve(equa, {T[air](t), T[sol](t)}, type = numeric);

but it shows an error :

Error, (in dsolve/numeric/process_input) dependent variables cannot be assigned a procedure. The

 following do not meet this requirement: [T[air](t), T[sol](t)]

please help me to solve the problem