Ajax Call Did Not Get Result Properly When Use_Trans_Sid Set To 1

I am experimenting with phpsession. I set the php’s use_trans_sid to 1. So phpsessionid propagate to urls.

But AJAX calls did not get result properly as it should before I set use_trans_sid to 1. Somehow the result is truncated.

When I set use_trans_sid back to 0, AJAX calls get result properly.

What would be the problem?

Thank you.