Check that you have the most recent version of Test Script Builder (J05).
Also check the firmware on your 2612B (3.4.2 is most recent).
Test Script Builder is making use of NI-VISA for communication with the instrument.
From error screen, it is not clear what the issue is.
If you have NI-MAX installed, try verifying basic VISA IO from that.
If you still need help, tell us the VISA resource name that you use for the 2612B.