DXF & .tiff files being place at completely different locations when adding as background files

Hi,

I have exported and aerial image as a .tiff file and route of a pipeline as a DXF from QGIS. The pipeline traverses the area covered by the aerial image. 

When I import them as background layers in WaterCAD there end up in completely different areas, 1 in the USA and 1 in Antarctica  (I have Bing Map background as well).

Both files in QGIS have their CRS set to GDA94 / MGA Zone 54 (EPSG: 28354).

Does anyone know how I can get these both in as background files both in same location? And ideally in the correct location in reference to the Bing Map as well?

Thank you