@Charan:arrrey! u have to give all secondary groups along with -G in usermod command.for that,use "groups" command in local user terminal to identify the groups where local user is member of.also restarting or teliniting system to runlevel 1 and return to runlevel 2 to have ur changes applied.best way is to use menu System>admin>user&groups and enable all needed permission and try restarting!