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
Start with some of our most frequented solutions to get help installing your software.