[Anonymous]

Hi mozyilmaz,

Thanks for posting on the Support Community.

With regard to this issue, please can you ensure that your cables behind the ActivBoard are connected and secure? 
Below is an example of the 300 series ActivBoard:

Should all be connected and secure, please contact Promethean Technical Support directly and providing your serial numbers so that the warranty can be checked.

Kind regards,
Adam
Promethean Technical Support