This is strange but i can't replicate the issue. I enabled all options and then made my sim to work out, the skill got upgraded fine.
Or is it some other bug you're having ?. If you're sure it is because of the no needs cheat, when you're close to having your sim reaching next skill level, disable the cheats (the needs don't go down that fast) and then re-enable.
Please let me know if this helps.
PS: like i said in other thread, i should have been contacted about it instead of a thread brought here since it is NOT cheathappens work and technically they can't assist you. Their sister site Cheatscapes is a marketplace for other authors so the respective author should be contacted, not ch,
Anyway i guess the average user don't know/care about the full details.
PS2: forgot to mention it has been tested for sims 3 pets only and on the worldwide release. You can check out which version you have if you don't already by opening skuversion.txt file in sims 3 directory and noticing the value on first line from right. e.g i have this GameVersion = 1.26.89.013002 Since it reads 2, i have the worldwide release (UK/EUR), if it is 1, it should be US cd/dvd release and for digital download, it would read 17.
I am not sure how this affects the game though and if there are any changes in the exe but if the above solution doesn't help, send me your game exe and i'll have a look.