Could not able to use serial ports

I'm using pxie-8861 Controller with LabVIEW RT installed. Total 4 Pxie 8431 and 2 Pxie 8430 serial cards installed in my RT system(96 ports).The problem is that I could not able to use more than 64 ports and it is throwing a error if go more than that. Earlier I used serial 19.5, with that in NI Max itself more than 2 cards ports are not listed  Can anyone give me a solution for this issue?