Connections to the reference data repository can be a little tricky. Double-check that the DM Server where the job fails has connection information to the reference data repository in a location similar to the following:
C:\Program Files\SASHome\DataFluxDataManagementServer\2.7\etc\dsn
See what you have in a similar location for DM Studio (where you presumably can access the reference data repository in nodes at design time) and create something similar. From the DM Server management screen in DM Studio, you can create new data source connections.See the attached screenshot.
Ron