If the C-Pen 20/3.0/3.5 is connected to the PC before installing C-Pen Core it may cause Windows to load wrong drivers.

To check and correct this:

  1. Have the C-Pen connected.
  2. Open the Device Manager.
  3. Locate the Input Pen entry and C-Pen xx sub-entry.
  4. Right click on C-Pen device and chose Uninstall.
  5. Disconnect the C-Pen USB and reconnect it again to allow Windows to reload the drivers.
  6. Start C-Pen Core software and check if the C icon turns blue.