Anyone who PRESSURE COOKS here please?

You are using a 2 gallon cooker to only heat a half cup of peas with nearly no water. If you had at least a couple quarts of water and a bunch of peas (or what ever) you might just get some steam. That would seal the valve and let its temp monitor start to rise. All you are doing is evaperating about a cup of water (no presure) and maybe getting a little condisation out from under the valve due no pressure there to seal it off.