A feature of the ActivBoard firmware (v8.60 onwards) is the ability to tune your ActivPen should you experience an uneven response when drawing or writing on the ActivBoard. If the ActivPen is not tuned you may see gaps or missing pixels, an example of which can be seen below.
To tune your ActivPen, hold it a few millimetres away from the ActivBoard surface. You will see the Promethean flame in the top left corner change momentarily from cyan to dark blue.
The ActivPen is now tuned to the ActivBoard, and this process will improve the responsiveness of the ActivPen. Any previous issues with gaps will have been resolved. In the unlikely event that gaps appear whilst using a different ActivPen, you should repeat the tuning process as described above.
If the problem persists, please contact Promethean Technical Support.