Recently bought a used, cheap, tasco scope to put on my modified m91/30. Everything seems fine, except for one strange issue. And pardon my expressions, I dont know scope language. The knob on the top changes horizontal, and the knob on the side changes vertical. For some odd reason, when I went to sight it in today, the knobs were all messed up. If i moved the horizontal knob to the right, it went up. And when I moved the vertical adjustment up the scope went to the right. I actually was able to sight it in, but its very strange. Is this just because im using a cheap $30 scope, and should just expect this?