Before attempting to set up your variable, please Configure the Hach WIMS Client for a Server-Side Interface for LIMS.
You will need to select which interface you'd like to interface to. Select the "Interface To" radial button. From the dropdown select the interface by name that corresponds to your Hach WIMS Direct Server-Side Interface to Custom EDI Lab Data Files
You only need to select the interface, cross reference is done in LabCal (see LabCal Setup)