Client.Error.DeliveryInDoubt / Channel disconnected before an acknowledgement was received

It's because of the error in the ZEND_AMF Script.

To solve this problem make sure that:

* Your Adobe Flex function parameters and PHP function parameters are of the same number.
* The parameters of your Adobe Flex function are in the same order with its PHP function counterpart.
* All the Adobe Flex function parameters are of the same data type with their PHP function parameters counterpart.
* You assign a default value to the optional parameters in the PHP function.
* You pass a value to the parameters that are not optional.
* Finally, your SQL statements should be syntactically correct.