It's a typo in the usage error text, not the function name. Also, the error is probably occurring because the GetAchievementCriteriaInfo function has been split into two functions that take different arguments. See:
http://www.wowpedia.org/Patch_5.0.1/...eaking_changes
Speaking of typos, however, whoever named the NUM_LE_LFG_CATEGORYS constant (which doesn't seem to be defined anywhere) needs to learn how to spell.