You did something other than use Bootcamp Assistant to try to change the Bootcamp partition. This probably caused your HD to get messed up. You may have to format your entire drive, reinstall OSx, then start again with Bootcamp Assistant. Make sure you get all your data off your OSx partition first.
You will end up reformatting the entire disk again, do it properly, disk utility is not the way. Frankly (as Bob says) it is probaby too late already.
What if I simply remove the BOOTCAMP partition via the Disk Utility?