Why am i having trouble generating a report when i use a custom module.

I have built a custom module which is designed to track our Instrument install base and the service history on those instruments.

The issue i am having is that i want to run a report that shows what instruments need a PM during the next Quarter. When i work through the report wizard however no matter what metrics i try I cannot get data from the report.

I have even tried a basic column report where it should give me the account name of where each instrument is. I did this by filtering the field Instrument "is not" and the criteria "blank"

is there something i need to do to make the fields with in the module visible to reports?