ADC12QJ1600EVM: Time_out_error when using internal clock

Hello,

I've just taken delivery of both an ADC12QJ1600EVM and a TSW14J57 (rev. E), and have been trying to get to grips with them. 
When I try to program the ADC to use "OnBoard 50M Ref to ADC PLL" clock source, I get a TIME_OUT_ERROR message in HSDC Pro v5.20 after trying to capture data. 
I have been through the datasheet of both products several times and can't figure out how to resolve this. 

Thanks in advance.

 Finlay