Using vstest.console.exe TestCategory with equals and not equals

I am using SpecFlow to write Gherkin for automated UI tests. We have multiple tags (@smoke, @on, @off, etc.).

Test A has tags @smoke Test B has tags @smoke @off

These are translated to vstest test categories and do not include the @ symbol.

I want to run test A but not test B.

This is what is not working. It runs all @smoke tests. Vstest.console.exe mytest.dll /TestCaseFilter:"TestCategory=smoke&TestCategory!=off"

Any ideas?