Hi Murali,
I assume you are using Screen Personas 2.0. Tab caching/merging is an automation technique that simulates clicking on the configured tabs and fetches content for each of the tabs from the server and then merges the contents in the SL client. There are cases when the Dynpro program prevents clicking on other tabs until all of the mandatory information is provided and/or is valid. If the Dynpro program has such a validation, the SL client is unable to click on all of the configured tabs to fetch information for merging. When such a case is encountered, the tab caching icon on the upper right corner of the tab header turns red and tab caching is stopped. The user is given the chance to fill in or correct the data and send it back to the server.
Regards
Kranthi