Invalid mixtures error with multi-scale occupancy

[jlehmkuhl]

I am trying to do a multi-scale occupancy analysis in MARK of small mammals captured on a grid. My dataset is accepted, but when I try to run a model I get an error “invalid value for mixtures = 56” (exit code P30). The trapping grid is 7x8 = 56 and that is what I entered for Mixtures/Devices in MARK. There are 4 trapping sessions for a total 56 x 4 = 224 occasions entered in MARK. I checked the data file and the numbers are correct. Any solutions?