Hi Lindsay
Thanks for posting on the forum.
Please can you advise us if the pens you are using are identical..?
If the pens are identical it may just be that one of you pens is faulty.
If they are different could you possibly post a photo of them and provide a serial number of the board you are using them with.
Awaiting your reply
If you would like to contact us directly regarding this issue, please quote your reference number which we have created to assist with this which is 00419522.
Thanks
Alavi
Promethean Technical Support