Its working  fine in the search  webpart itself in the search centre Site ...

*what made me is to block to search Federated search in Federated Webpart:*
"I tried to add a Federated Search webpart  in the results page  and i have
given the search option as "new content  Source(external website)" This made
me blocked to search external  website in the Federated webpart..."

In the normal search web part itself we can search the External Websites
Data..