I'm still a newbie too, so take the following with a grain of salt:
If you are getting a constant beep with all elevations, your meter isn't adjusted right.
If you are using the SF-90 meter, most of the time, you want the needle in the middle, just starting to make a noise. Keep tweaking the knob to keep the needle centered, each time you adjust the dish slightly to peak the needle as best you can.
I'm going through this myself, so I know some of the trouble/frustration you might be having. You might also be pointed at the wrong satellite (off by a couple of degrees), or you might have the frequency/polarization/symbol rate off.
Your LNB should be within 5 degrees or so of the perfect skew... it's not nearly as critical as the dish
aiming.
Another thing is that the 90cm dish has a narrower "main lobe" than the smaller dishes, which means you must point it more accurately. The upside is that you will get a stronger signal, and have more ability to reject nearby satellite signals.