How can I get the game gnome to beocme activated on Sims 2 for Ps2??

Ok i put in the cheat for the gnome and its there. then after i went back to the pause screen and entered in the cheat for set all skill levels but when i did i heard the ahhhhh thing and then i went to the gnome to activate the code and no drop box or anything was there saying what cheats i put in. Can someone please thouroughly and clearly explain how to do it. When i go up to the gnome and hit x it jsut makes a sound like i cant do it or sumthin….i need this because my sim cant reach level 6 in her career and her things to get promoted are full she just is not gettin promoted. PLEASEEEEEE HEEELLLPPPP!!!!