Vacuum breaker Question, Pic included

When I put my pressure tester on this faucet it would leak water
around vacuum breaker…I could not test the water pressure.

Is this normal or is the vacuum breake defective ?

http://i187.photobucket.com/albums/x296/dawlita/Pic014.jpg

Sometimes the plastic part in the valve gets stuck / clogged. I have that happen once in a while when I turn on the faucet real slow. Usually turning it off and back on real fast lets the valve re-set.

Or it could be bad.

thanks