Why can't I communicate with the Ethernet I/P option on a HI 3000 series controller?

I have a HI 3000 series unit with the Ethernet I/P option installed. I have set up and can ping the address with good results. RS Linx also sees the unit on the network. But my Compact Logix processor shows a communications error and cannot get my unit online. What could be the problem?

Normally if your HI 3000 series unit (which includes the HI 3010, HI 3030, HI 3300 and the HI 3600) shows up in RS Linx and you can ping the address, then the unit is working. When this is the case but the processor has a communication error, it is usually caused by a setup error in the I/O configuration. Most commonly, the "Comm Format" in the setup defaults to DINT. This needs to be changed to INT for the communications to operate properly.

The configuration for the setup is:
Comm Format = DATA INT
Assembly Instance:
Input 100 size varies (0 to 125)
Output 150 size varies (0 to 125)
Config 1 size 0
RPI = 20 ms (minimum)