ad9552 dc bias input changes to higher value

Hi,

I am using AD9552, reference input applied a 40MHz clock signal.

I am using AC coupling, I applied 1V dc bias with resistor divider from 3.3V power supply.

A0-A2 are connected high. Y0-Y5 are open. xtal is connected.

I see 40MHz clock at 1V bias at input when I switch on board.but after I program the chip I do not see the clock chip output.

I check the input it becomes 40MHz with >2.5V DC bias,

can any one help me to figure out what is going on?

I removed the xtal and checked again the problem is not solved.

Thanks in advance

goal