Fisher reaction PDE propagating from a point source

Hi,

I'm using pdepe to solve the nonlinear hear equation

$\frac{\partial C}{\partial t}=r^{1-s}\frac{\partial}{\partial r}[r^{s-1}D\frac{\partial C}{\partial r})] + u(1-u)$ where $s$ is constant and $D=D_0(\frac{\partial C}{\partial C_0})^n$ and $n>0$

The initial conditions correspond to propagating from a point source, but I can't find appropriate boundary conditions that Matlab will accept. I keep getting the error "Error using pdepe (line 293) Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term involving spatial derivative". Can anyone help me?

Thanks!!