Brake booster question

I bought a new booster/master cylinder for my Duster.

I took the master off the booster to paint the booster.

I put a vacuum gauge on the car today and had almost no vacuum on the small nipple at the booster. I pulled the fitting out of the booster and there was no difference in vacuum. I put my finger over the inside of the booster fitting and the vacuum went up to the normal range on the gauge.

So I'm thinking the booster can't build any vacuum at all. I must have assembled the master and it's gasket/spacers wrong that keeps it from sealing, or the push rod from the booster to the master cylinder is in there wrong.

Any thoughts?