Question: How to use function in boundary condition?

Hi !

I am trying to solve a pde with initial/boundary conditions, in the numeric mode. It works very well when I provide 3 numerical conditions : 1 initial condition (uniform distribution at first), and two boundary conditions.

Now I want to switch the initial condition to a function of r. It's a polynome I obtained after interpolation of another result. I tested it and the function interp20(r) works. But the pdsolve doesn't seem to evaluate the function, when it comes to start the procedure and pdsolve doesn't return a module as it should, although it doesn't send any message error.

You can see the code following, with the error messages I get.

Is it strictly impossible to use a function as an initial condition ?
Is it just a problem I could solve by converting the function or its result to something else ?
Is float the right type of input ? For example, if I write a:=283.15, is it a float ?
Have you already had similar problems ? How did you solve them ? Where could I find working code examples on this ?
Could I solve this problem with non-uniform initial condition with another Maple function ?

Then you very much for your help !