Repeat group - continu repeat while response equal to 'yes'

Hello, I'm using a repeat group in my form. Now in the repeat count field, I want to ask the user if he wish to continue. If he says yes, the user stay in the repeat group else the survey continues. The real problem is that the repeat count field doesn't accept response='yes'. Your help please

usually if you leave that field empty "repeat count" you will get an option to add more repeats. but it doesn't behave the same way in the emulator.