Hello Sumant,
What do you mean by Single Transaction Check and Integrated single transaction check.
What are external transactions?.
I read following two links:
http://help.sap.com/saphelp_erp60_sp/helpdata/en/1e/6ae4382763855ee10000000a114084/content.htm
http://help.sap.com/saphelp_erp60_sp/helpdata/en/02/a1ed39fd9be737e10000000a11402f/content.htm
But I am unable to get these things. Is these settings mandatory?.
Also I did 5 steps mentioned above. There is no additional setting in the link given to you.