GPIB connection fault after checking connection in NI MAX

Hi,

I have a problem with a system I am using.

I am connecting to 3 Keithley 2410 power supplies in labview using the Agilent 82357B USB/GPIB Interface.

The labview program works... but if I check the GPIB connection in NI MAX or in Agilent connections expert before/ during using labview then Labview can no longer connect to the power supplies. It can originally connect to the first two and then the third connection fails following by them all failing.

Any help would be much appreciated,

Thanks

E