This is part of the game as well, I had to add in levels up to 250 to get higher levels... the game itself sets a certain amount of levels "in reserve" for levels that are only attainable via completing items or leveling a chibi. Try adding some levels in under the configurations. Make sure that you do the experience correctly as it is rolling experince... IE: the experience you put in is the TOTAL amount needed, not just the amount needed for the level.
Ex:
Level 1 5
level 2 10
level 3 15
each level needs to be higher than the last, even if just by 1