I use MSTestRunner in a parameterized build to define the test category I want to run from the user interactively choosing the name of category in a dropdown list when starting the build. According to the parameterized build plugin, the variable is defined as an environment variable. I can access to its value successufully using %UserChoice% from a batch command inside the job. However, the MSTestRunner plugin does not accept to read %UserChoice% when I type it in in the TestCategory field. I get an error (see attached screenshot): "the model of the chain is not valid"