First off you might be like me and have to translate many years of using “Image” for the Menu or Ribbon tab name to “Raster Tools.“ It is now "Raster" for the Menubar and "Raster Tools" for the Ribbon.
Next double check that you have a Workspace loaded.
Then check that the Partial CUI for AutoCAD Raster Design 2011 is loaded:
Vista and Windows 7: C:\Users\%username%\AppData\Roaming\Autodesk\ARD2011\R18.1\enu\Support\AecCo.cuix
XP: C:\Documents and Settings\%username%\Application Data\Autodesk\ARD2010\R18.0\enu\Support\AecCo.cuix
AutoCAD Raster Design 2011 also requires these additional Support File Search Paths:
C:\program files\autodesk\raster design 2011 oe
A user profile folder:
Vista and Windows 7: C:\Users\%username%\AppData\Roaming\Autodesk\ARD2011\R18.1\enu\Support
XP: C:\Documents and Settings\%username%\Application Data\Autodesk\ARD2011\R18.1\enu\Support
C:\program files\autodesk\autocad raster design 2011
C:\program files\autodesk\autocad raster design 2011\help
Let us know how things work out.

Douglas Lauritsen
Support Specialist
Product Support
Autodesk, Inc.