I'm pretty certain you don't have to select a column in order to use it in a join like that. I wonder if a) the column name is indeed incorrect or b) you might want to add alias names to your tables like:

... from csGroups_lang cl, csUsers cu, csGroups cg, csUsers_Groups cug, where ... cug.UserID = cg.ID ...

Hope this helps, I know this isn't a complete answer ...

mr.dunstan
"There are only 35 chambers, there is no 36th."
"I know, I want to create a new one... " - Shaolin Master Killer