TestLink-how to add test cases in bulk to a test plan?

I am trying to add test cases to test plan in testlink through the option on home page that says add/remove Test cases.But the problem is when i select all the test cases and click add to plan,only 249 cases are added the plan and rest are not.Even if i try to do it again i does not add more cases.Looks like the count is set to 249 somewhere. Any help will be appreciated!