We won't be able to help unless we can get more information. Most people tell me this works though.
Latest version of Joiplay is realy buged. I tryed to run many different renpy games - absolute fail. Probably it is a problem with Joiplay emulator itself and it renpy plugin. The only thing that can be done - deleting the latest emulator update and find the previous version (v1.01.400 for emulator itself and v1.00.40 for renpy plugin).