Start swapping components around. You already know the boxes are good; they work on your home setup. Swap out the LNB on you home unit. Just be sure not to knock the dish out of alignment. If the LNB is good, I'm guessing a bad cable or connector somewhere. Do you have a the sat meter? One thing it is good for is making sure you have voltage at the LNB; it won't squawk unless it is getting power from the box proving your cabling is good. Also verify dish type and LNB type is setup correctly in your configuration.