[otrs] language changes

Hi, I want to adapt (and correct) some of the words in my language file to be consistent in Swedish all the way. When I do so in my case sv.pm and choose sv as the language then I only get the following error: ---- Can't locate object method "Data" via package "Kernel::Language" at /opt/otrs//Kernel/Language.pm line 129, <PRODUCT> line 72. ---- This happens if I make a copy of the original sv.pm and rename the new file to sv.pm and rename the original file to sv_org.pm. I also change the owner and modes to be the same as the original. I don't know if this is the way to do the changes or if there is an option in the SysConfig option in the admin area? Anyone the has the same problem? Thanks in advance ricfors