Project is completed and buyer also tested the project and he is satisfied but he is not responding

Project is completed and buyer also tested the project and he is satisfied but he is not responding. He said he need payment from his directors to complete my invoice. I am worried i said the project was between you and me, 24 hours has passed he was online few hours ago and he read my messages but he did not replied.  i am worried to much. I think you need to review your payment policy. This is the second time i am facing the same issue. I am not worried about the escrow amount but 70% amount is not covered in escrow. 

Please review the policy it is second time happening to me.