What stats are required to be a member of the thieves guild?

I don't think there are any specific stats to join the Thieves Guild. You can join and then advance by getting the following skills up: Marksman, Short Blade, Light Armor, Acrobatics, Sneak and Security.

In order to join, none, however there are stat requirements for certain skills (light armor, sneak etc) in order to advance in rank within the guild.

Maybe it's bugged then? I have all primairy stats 50 or well above and at least all 10's in the favored skills. Sugar-Lips just tells me I dont have what it takes. My only rank at this time is Guardian for Fighters Guild, but Im not finishing that one cuz of the last fighters guild mission. Strange...

Did you kill one of them or steal from them while working for the Fighters guild?

Erhm, nope. The only encounter I had with them so far is when I retrieved the code book from sottilde.

hmm..did you check out the requirement for the next rank?

Yeah,
Agility & Personality > 30 : CHECK
One Favored Skill > 10 : CHECK (got all favored skills above 10 for Thieves)
He just says: We have our standards and you do not meet them dunmer!
BASTARDS!!!

let me see...you got the skill requirement correct. hmmm...did you do remember to do their quest? or have you finish all sugar lips quest? try other thieves guild in ald ruhn or sadrith mora.

the other thing that struck my mind now is the word bug. :(