MAX1415

I'm attempting to write a micropython driver for the MAX1415 ADC and having difficulty getting it to work when I want to use and external Crystal for the Clock...
Everything works fine when set up for internal clock (Clk Register = 0b101000101 = Internal Clock, 2.4576MHz clock, Output data rate of 60 Hz).

I'm assuming by setting the Internal Clock Enable Bit to 0, disables the internal clock, allowing the crystal clock to prevail (2.4576MHz crystal)..
So, setting the Clk Register to 0b100000101 should work, Right??...  Nope....
The crystal is working, CLK Out pin shows a stead 2.4576MhZ 3.1V P-P clock signal, but the A/D functionality stops working... (Data RDY never goes Low...)

What am I missing?