Did you recently complete your application? Applications take about 24 hours to process! If it is still being processed, you should be added to the group once that's completed.
Was your application processed and completed? Most likely the address was not inputted the exact same way. The address entry needs to be identical to your roommates' account. No problem! Just renew your account with the correct address, double checking the spelling of the street name, city name and zip code.