array too small error

Hi, I've been trying to create a homology model using three templates. Modeller got to the point of "Restraint type to be calculated: distance", then gave me a lot of warnings that "Two basis restraints have means too far apart" and then quit altogether giving me an error "Array too small. Increase MPRMCNS, current maximum, current need: 812700 813746". What does it mean and how can I fix it?

thank you very much,