Hi kavitha,
Please try below workaround:
please start the configtool and navigate to:
Global Server Config -> services -> com.sap.security.core.ume.service
select the property ume.r3.mastersystem
Enter a valid mastersystem here or leave the field empty.
Save your changes and restart the j2ee engine.
Please use the workaround from note: 791649 as well.
Also have a look at the 'security provider ->ticket' and check the
settings for the login module as per the below:
http://help.sap.com/saphelp_nw04/helpdata/EN/aa/
bf503e1dac5b46e10000000a114084/content.htm
Kind Regards, Premsukh