Carbonation

I have made 4 attempts at brewing bottles. First one was flat. I screwed up the conversion. Okay, then the second one was flat and sour. Third one was a different recipe and all grain. Very foamy. I lose about half the beer when I open the bottle. Fourth batch, same recipe, is flat and sour. I've allowed a month for bottling, left at room temp. I guess I have two problems: Why does the beer get sour, and why can't I get consistent carbonation?

Sorry you're having tough luck right off the bat!  How big are your batches?  Tell us more about the brew process... specialty grains with extract?  What type of brew?  How did fermentation go?