Well, X and Y are definitley dependent, it is always [tex]E[Y] = cE[X][/tex].
Does that help??
If not, what more information is needed??
In the paper I have about these bivariate Poisson distribution it also states that [tex]P(X|Y) = d/(c*mu + d)[/tex] and also [tex]P(Y|X) = d/(mu + d)[/tex], if that's any help?