The Edit to Tape features in Final Cut Pro require precise device control in order to accurately start and stop recording at the desired timecode locations on tape. If the Insert Edit or Assemble Edit buttons in the Edit to Tape window are not available (don't respond to clicking), you may need to modify the settings on your video recorder. Most professional video decks feature on-screen menus which allow a number of the device's settings to be displayed and changed.
For details about the capabilities of your video equipment, check the documentation that came with it. For more information about equipment requirements for using Edit to Tape features, refer to the Final Cut Pro User Manual.