potty training woes

I am so ready to be done with the potty training struggle. It's been going on for months and months, off and on. Lately, Elijah has some days that he does really well-the last day and a half were really great- and others where we bomb out. Last night I was ready to pull my hair out--poopy underwear, pee pee on the floor and all. AHHHH!!! I believe Elijah knows what he is doing, which is the most frustrating part! He will go and hide sometimes instead of using the potty. Am I going about this the wrong way? Am I expecting too much? We have tried potty charts- they stay up for weeks unfilled; he's not always interested in treats or rewards. I'm just burnt out! I'm loosing hope of ever getting poop in the potty let alone in the big toilet. Any suggestions, encouragement? HELP!