Creating a mosaic database in ArcCatelog and when I try to add data raster to my newly mosaic file, I keep getting this error message: 8004205f: no new mosaic item was added. I have looked on this sight for similiar issues but did not find anything that could help me with this issue.

I am bringing in the raster from layers that have the bathymetry, relief and multibeam. Ideally I want to create the mosaic with the multibeam, but still can not work this out. I have tried to just use the mosaic to raster tool, but this have come up with it own errors.
Any assistance would be great.
Thank
Jess