What is the version of your NI-488.2 Driver?
Here you can find the
Latest Driver for your GPIB-ENET/100. MAke sure you select the right Operating System that matches your machine.
Once you have checked and updated the NI-488.2 Driver then you can try and bypass LabVIEW. Use the IBIC command interface. You can start it from
...\Program Files\National Instruments\NI-488.2\bin
That is the low level interface that lets you take control of your instrument without using any Application Development Environment.
Regards,
AlessioD