How we add a user group in RTC 2013 R2

Hi everyone,

i am new in NAV 2013 R2. i 've added the user group with windows group license type in RTC 2013 R2 .
my usergroup contains two user as (navtestuser1 and navtestuser2 at local system) ,when opening the RTC with any of the user it gives this error :
"you donot have access to microsoft Dynamics NAV .Verify that you have been set up as a valid user in microsoft Dynamics NAV" .

pls suggest me solution .

pankaj yadav