in my opinion they are modified the previous version with newer version of OPNET and as you know OPNET is not really friendly with Backward Compatibility. so when they saved it with opnet 16, it can't be open with the previous version anymore. i can run the file with opnet 16, but the license is only for 1 PC so usually i have to use the 14.5 version.
i made the model according to their approach but when i simulate it, i got some external files problem related to geo_earth_ function from closure_support external files and i can't solve it yet.