Bob,
I have used the E1406 GPIB Controller before. I had a couple of problems with using this controller, which may help you out.
NI-VISA supports multiple GPIB-VXI controllers in a single system. Because the National Instruments GPIB-VXI controller ships with a primary address of 1, NI-VISA automatically searches for any GPIB-VXI controllers at that address.
If you have changed the primary address (for example, if you added a second GPIB-VXI controller to your system, and set the address of the second controller to 9), or if you have a GPIB-VXI controller from another vendor, you need to add it using Measurement & Automation Explorer so NI-VISA can find it. Right-click on "Devices and Interfaces" and select "Create New" to add a new GPIB-VXI interface.
Specify the controller's GPIB primary and secondary addresses, as well as the GPIB board to which it is connected. Then specify a new GPIB-VXI interface number and its logical address (usually 0).
Also, make sure that Servant Area address is set higher than all of your addresses (Dip Switches on HP 1406). If you have your Servant Area set lower, you will see your instruments in MAX just fine, but you won't be able to communicate to them at all.
Joji