GateKeeper module is a licensed salespoint. A ScanMan station must be on the Sales Point Licenses grid in SysManager > Preferences. To add it, go to SysManager > Activities > System Lists > Salespoints > New and create a new salespoint in ScanMan mode.

When you click New, you are presented with the following dialog:

 

 

The salespoint name for GateKeeper assigned in SysManager and the salespoint setting in Gatekeeper.INI need to be exactly the same.

You can also select the mode from the SysManager > Activities > System Lists > Salespoints > New/Edit > Licensing tab on the Salespoint Configuration dialog.