There are one of 2 things happening:
1.) Ensure you are using the correct command. It's a Map 3D command so a normal image insert does not have this option. The Map 3D command is MAPIINSERT
2.) Do you have the raster Design Object Enabler installed? This is required to give us this support. You must download and install this free add-on from the Autodesk website.
Civil 3D - http://usa.autodesk.com/adsk/servlet/ps/dl/index?siteID=123112&id=2334440&linkID=9240698
Map 3D - http://usa.autodesk.com/adsk/servlet/ps/dl/index?siteID=123112&id=2334440&linkID=9240858
After downloading close all versions of AutoCADDouble click on the file you downloaded and follow the prompts. As with any Autodesk install you must have Virus
Scan disabled and must have administrative rights. During the install only.