Usually when we see this it is because that particular installation of ROBOTC does not have an active license or trial attached to it. If there is a Virtual World license (but not a ROBOTC license), you will be able to compile to a Virtual World but not to a physical robot.
Double check to make sure you have a valid ROBOTC license active; to do this, navigate to the 'Help -> Manage License' menu option in ROBOTC to check for a license. If you need to activate a new license, you can use the 'Add License' option to enter and activate your license on that computer. We also have a wiki page dedicated to setting up and activating ROBOTC
that you may wish to look through.
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Need help? Take a look at our updated help documentation
and the ROBOTC Forums.