I'm not sure what other mods you've installed, but after two days of installation, I discovered that you may need multiple mods for them to work properly. I installed Arrest Manager, Better EMS, LSPDFR+ and Traffic Policer and it was when I installed those four at once did my LSPDFR work - so try that. After that I installed the Smart Radio and Computer + (in that order, and not combined) and so far things have been installing a lot more smoothly.
Just a suggestion as I just bought the PC on Thursday... good luck! :)