Need help programming Due clone with Atmel ICE in Arduino IDE

I have a custom board based on the Arduino Due. I also have the Atmel ICE programmer, and I'm trying to load code to the SAM processor using the ICSP header within the Arduino IDE.

In Arduino I have have selected Board as DUE programming port, Programmer set to Atmel ICE, (have also tried Atmel SAM-ICE), If I then click Sketch/Upload Using Programmer, I keep getting the error message "Please select a programmer from the Tools>Programmer menu"

Anyone have a clue what I need to do to get this working properly?

I've checked the windows device manager, and can see the USB Human Interface Device drivers that were loaded when I first plugged in the Atmel ICE device.
The LEDs on the programmer are red and green, showing it's on and target has proper power.

Any help would be appreciated.