When you get this error message it means that the CAN port is working on the tachograph, but the remote download wasn't enabled in the tachograph.

In the Stoneridge tachographs normally you can enable this with a service card.

In the VDO tachograph you need a programming tool like CTC II, MK II, Digitachytest 2 or any other programming tool that can enable the download on CAN2

If you are using the unit in the front download interface K-Line protocol with a VDO tachograph then you need a VDO unlock card to enable the remote download.