How to unassign/delete usergroup from role progmatically in Liferay 6.2

Question

Im trying to remove usergroup from role using the following method. But it doesn't work. Can some one help me to identify the problem?

  public static boolean  deleteUserGroupFromRole( String groupName, String roleName )
    {
        try
        {
            company = CompanyLocalServiceUtil.getCompanyByMx( PropsUtil.get( PropsKeys.COMPANY_DEFAULT_WEB_ID ) );
            long companyId = company.getCompanyId();

            UserGroup lportalUserGroup=   SoasLportalGroupHelper.getLportalUserGroup( groupName);
            Role role=  getRole( companyId, roleName );


            GroupLocalServiceUtil.deleteRoleGroup(role.getRoleId(), lportalUserGroup.getGroupId() );

            logger.debug( "Role : "+roleName +" has been deleted from groupName "+groupName);
            return true;
        }
        catch ( PortalException e )
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch ( SystemException e )
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return false;
    }