Thanks Sunny for your solution. May be I have not framed my doubt clearly.
I found the solution from your reply on
Could you explain the expression that you used in above link?
Just adding a couple of Design Blog URLs to posts that may help in explaining things...
Hopefully these may fill in the gaps you have, be sure to give Sunny credit for the help by using the Accept as Solution button on the post that got you what you needed, or mark the post with the link to his prior post...