cancellation of a foreign expert certificate in China

Can anybody help me with one problem? Maybe somebody has faced it before? I worked as an English teacher in China for 1 year. Now my contract is over and I am back home. I want to come back to China and have found a new employer, but now he told me that there is a problem because he can't apply for a new Foreign Expert Certificate for me because my old employer hasn't cancelled it after the completion of my contract. The matter is that my foreign expert certificate was kept by the school where i worked and my former employer promised to cancel it when i leave China. What should i do in this situation and can i get a new foreign expert certificate?