What's the offer, what's the angle, and what's the traffic source?
Could be anything although initially I'd say that you need to test more banners, probably in more sizes and more placements.
This is like asking "How long is a piece of string"!!!
Well, your first problem is you burnt $90 on a $1.40 offer without making any revenue.
Your CPCs rival the offer payout and you'd need a 100% conversion rate from banner to offer to break even.
You definitely need to pay closer attention to your metrics and make faster decisions.
This campaign should never have had the chance to spend (burn) so much $$.
More info please!