What software are you using?
If you are getting a message like that most likely is product of a bad install, please run a reinstall of the software from the control panel.
+ adding to Tatiana:
>> What software are you using?
What profile is active? If you run Civil3D with the profile "as AutoCAD" then the AECC-commands are not available.
- alfred -
Log into access your profile, ask and answer questions, share ideas and more. Haven't signed up yet? Register