First step, recheck your measurements; how are you measuring? Is/could your measurement be off due to calibration or temperature? If you measured your OG at higher than the calibration temp, did you adjust (I always cool a sample and do all my measurements with the same hydro at the same temp)? If not, your OG will be understated; if the beer is fermenting at a lower than calibration temp then your current gravity reading could be overstated.
I don't know which kit you have, the only vanilla stout I see is a mini-mash with a projected 56pt OG, the other stout kits seem to have 45pts as the very low end of their predicted range.... this leads me to think your OG measurement is probably off. If you know how much extract you used, you can back into the gravity based off of the PPG and volume of wort.
Are you fermenting in the proper range or did the wort get too cold and cause the yeast to go to sleep?
To answer your original question, I am an AG brewer and use dry yeast extensively and have never had a problem, I seriously doubt that the "dry" in the yeast is the source of your problems. If still in doubt that it's not done, dry yeast is cheap, properly rehydrate another package and pitch!
Good luck.
Werbi