Any automatic pool vacuum experts out there?

[Spoisal]

We opened our pool yesterday - we had it built in the fall & have not used it yet. Everything seems to be going well - water chemistry, heater, etc ...except for the Ray Vac pool cleaner that we have. It doesn't seem to be cleaning! (it is moving around, but doesn't seem to be sucking much dirt/debri). I have been reading things about booster pumps & cleaners that don't need a booster pump, etc. Before going to the expense of getting a booster pump & a cleaner that works with a booster pump, any tips on how to get this Ray Vac working more efficiently?