Question: Rational function error. Please help how to define constants to do parfrac.

Hi!

I am a relatively new user of Maple. I am trying to find the partial fractions of a polynomial expression. All the values are constants determined by an outside system (that I am trying to model). The function is in terms of s. The denominator was simplified via substitution (more combinations of constants) to see if I could find the problem. There is no other code in the file, so I don't know if I have to define the constants (Cdl, RL, R1, R2, C1, C2) separately.

f:=(V[0](s^3+(2 s^2)/(C[dl] R[L])+(s^2)/(C[2] R[L])+(s^2)/(C[2] R[2])-(s^2)/(C[1] R[L])+(s)/(C[dl] C[2] R[L]^2)+(2 s)/(C[dl] C[2] R[L] R[2])+(s)/(C[dl]^2 R[L]^2)-(s)/(C[dl] C[1] R[L]^2)+1/(C[dl]^2 C[2] R[L]^2 R[2])))/(s^4+as^3+bs^2+cs+d)

convert(f, parfrac, s)

Running convert parfrac gives me an error that the argument is not a rational function. Any help is greatly appreciated!