Question: unable to solve system of pde

Hi,

I am tring to solve two coupled pde's with piecewise/Heaviside conditions. I am puzzled with the maple error...Rhop, Rhos are constants n given some values..

> pde_sys:=[diff(c(m,t),t)=(2/m)*diff(c(m,t),m)+diff(c(m,t),m,m)-(convert(piecewise(d(m,t)<Rhop,(Rhop-d(m,t))*d(m,t)*c(m,t)),Heaviside)+(Rhos-d(m,t))*c(m,t)*convert(piecewise(d(m,t)>Rhop,Rhop,d(m,t)),Heaviside)), diff(d(m,t),t)=convert(piecewise(d(m,t)<Rhop,(Rhop-d(m,t))*d(m,t)*c(m,t)),Heaviside)+(Rhos-d(m,t))*c(m,t)*convert(piecewise(d(m,t)>Rhop,Rhop,d(m,t)),Heaviside)];

>bc:={c(m,0)=0,d(m,0)=1,c(1.01,t)=pc[1],c(1.02,t)=sc[1],d(1.01,t)=(1-0.1)*Rhos,d(1.02,t)=(1-so)*Rhop};

>pde_sol:=pdsolve(pde_sys,bc,type=numeric,time=t);

i got the following error...

Error, (in pdsolve/numeric/par_hyp) Incorrect number of boundary conditions, expected 2, got 4

i am confused since i m solving 2 pde's =need 4 boundaries, but maple error says it expected 2 not 4

please comment on this.............

thank you,

manohar