Creating a Loop multiplying the binomial distribution times poisson distribution.

I am trying to sum the results of binomial distribution time poisson distribution as follows:

symsum(binopdf(k,6,.7)*poisspdf(k-2,6),k,0,6)

But it keeps giving me an error. How can I sum these two or varies values of k? I actually want to create a loop with i and j for a matrix as well.