How to assign values to variables in mupad after symbolic evaluation

Dear All

I am using mupad andn trying to solve a set of equations each of which is recursive in nature and one function call the other. After sucessfully evaluation the answers symbollicaly I am trying to assign the value to the variables but not been able to do so successfully.

I am writing following equations

Ct := Z -> Z^(RTS+EIFS); St := Z -> Z^(RTS+CTS+ACK+3*SIFS+DIFS+ld); Hd := Z -> ((1-pc)*(Z^slottime))/(1-psuc*St(Z)-(pc-psuc)*Ct(Z));

HW := proc(Z,i) begin return(piecewise([0 <= i <= m, sum(Hd(Z/(2^i*(CWmin+1)))^j,j=0..2^i*(CWmin+1)-1)],[ m < i <= alpha,HW(Z,m)])); end_proc:

H := proc(Z,i) begin return(piecewise([0 <= i <= alpha, product(HW(Z,i), j=0..i)])); end_proc:

B := Z-> ((1-pc)*St(Z)*(sum((pc*Ct(Z))^i*H(Z,i), i=0..alpha))) + (pc*Ct(Z))^(alpha+1)* H(Z,alpha):

diff(B(Z),Z)| Z = 1

the last statement should be more precise as

mu = diff(B(Z),Z)| Z = 1

The value of RTS, CTS, DIFS, SIFS, ld , n , pc, psuc, slottime are known to be. Z is dummy variable and is evaluated to one after differentiation is over. I except the resultant of final equation to be in mu. When i assign the values to my varibales and write mu on command prompt I get the error telling me problem concerning MAXLEVEL . Kindly help me in evaluating the probelm.