When trying to steal from the halfling merchant in the grove, I try to steal his money with a DC 19.

I have +8 to sleight of hands and advantage thanks to Improve Capabilities. While I can steal lower DC items, I cannot steal those coins even after multiple (8) reloads (yes, I know).

Anything over or egal 11 should have succeed. Statically advantage give around +5. So virtually I should have 70% chance of success.

How comes despite multiple atempt I cannot succeed this check ?

Notes:
- karmic dice is disabled
- I did this after using Disguise Self