[R] MLE

[pari hesabi]

Dear Sir/Madam
I am trying to get the Maximum Likelihood Estimation of a parameter in a probability mass function. The problem is my pmf which includes a summation and one integral. it is not similar to other known pdfs or pmfs such as normal, exponential, poisson, .....
Does anybody know whether I can use the current packages(like Maxlik) in R for getting the MLE of the parameter?
Can anybody explains me with an example?
I would appreciate any help.
Best Regards,
Pari