SharePoint 2010 - Search not working for Claims based FBA we

Question

Hi

1.Search is working for Claims based FBA web application fine(Here we extend the web application and adding server name mapping,crawled extend web application). But when we use Custom XML site map providers search crawl will Raise a error like"The SharePoint item being crawled returned an error when attempting to download the item" and crawl will not return any result.Here we customize master page ribbon also i.e we set search box in ribbon,moved site actions in to right side,Help icon into ribbon also.

2.when we apply same changes for  Classic mode windows  web application working fine.

Please help if someone knows the solution.

Regards,

Hemachandra