Rocket 44 headphone jack

I seem to be unable to get my Mesa Rocket 44 headphone jack to work. I have an adapter for the small headphone plug (1/8" I think) to 1/4" plug, which works fine when I use the headphones with my stereo amplifier, but won't work with my Mesa. Am I missing something? Would the Mesa take a different kind of 1/4" adapter than one that would be appropriate and usable for a stereo receiver? Anyone have any input, it would be appreciated-thanks.