After using LoadBuilder to import demands into a mode, either no demands are added or demands are all assigned to one node. A similar issue could occur when assigning customer meters to nodes in LoadBuilder; the associated element of the customer meter is blank after completing the steps.
Check to make sure that the correct demand alternative and/or scenario haves been selected to reflect the changes. LoadBuilder has an option to create new scenarios and alternatives. If the updated scenario is not the active scenario, or if the active scenario does not use the new demand alternative, that can give the appearance that the import was not successful.
Confirm that the shapefiles used in LoadBuilder line up with the model. Add them as a background layer to visually inspect. Use the same units specified in Loadbuilder. If they do not line up, then all loads could be assigned to one single node on the edge of the model (since it would be closest to all Shapefile features). For LoadBuilder methods that utilize a service area layer, you may encounter an error stating that no loads were assigned.
If you find that the model does not line up with the shapefiles, it could be due to a number of reasons. For example, you may have chosen the wrong units (feet vs. meters), or the model may not have been drawn in the same coordinate system, in which case you may need to move it manually or reproject.
If the data in the shapefile was created with a different unit than the model, you could try the following:
Troubleshooting and Understanding LoadBuilder
How to bulk change coordinates or scale up or down a model