If the payloads are fixed size, then there is no reason to use dynamic payloads. Furthermore, the length provided to write and read determine how many bytes are transferred over the SPI bus with the radio. You should make these the proper size. If in fact they are fixed size, then I encourage you to not use dynamic payloads. Instead, use setPayloadSize() with dynamic payloads disabled. On the other hand, if you are using dynamic payloads, you should use the API properly. If the API is not used properly, there really isn't any point in looking for other issues.
Also, you need to either quote your code, or use something like pastebin. It helps a lot. Furthermore, complete code dramatically improves things.
Do the examples work for you?