for about the last 7 thieves guild missions the guildmaster keeps telling me I have to practice my skills to advance a rank (I'm still a blackcap) is there a cut off on all my stats that would keep me from advancing if I don't raise them above a certain lvl, or do I just need to perform more missions?

Do quest for thieves Guild at Ald Ruhn, Balmora and Sadrith Mora. After that go to Vivee and do quest from Gettlemen Jim.

You might need to take up his optional glove quest to advance further.

Spoiler (Maybe)
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The 6 favored skills for the Thieves Guild are:
Marksman
Short Blade
Light Armour
Acrobatics
Sneak
Security

To advance to the next levels:
Rank..........AGI.....Per.....1 Fav Skill......2 Other Fav Skill...
Operative......30......30..........40............. ....10...........
Bandit.........31......31..........50............. ....15...........
Captain........32......32..........60............. ....20...........
Ringleader.....33......33..........70............. ....25...........
Mastermind.....34......34..........80............. ....30...........
Master Thief...35......35..........90.................35. ..........

Having your agility and personality at these levels and the above favored skills from the list above at the levels beside the rank, plus doing your "duties" will allow you to adavnce in the Thieves Guild. Hope this makes sense. :D

Mark

well put there skywalker.
if your ever curious as to why you cant gain a lvl in a guild go to your menu page and put your cursor over the guild of choice.
it tells you what your skills and or attributes need to be at to gain to the next lvl.

the two things a advancement question will ask you is:

you have done well with your duties but you need to do more duties to gain advancement.

the other is you have done well but you dont have the skills to advance in the guild

you got the second message