Counts setting in DAC AD5062

We are facing problem regarding SPI communication with AD5062 DAC .

we followed the data communication sequence as per the datasheet .

Ref voltage given to IC is 4.094V.

Pass the digital counts & got the analog voltage as mentioned below-

Count = 8000  , Output Voltage = 0.499 V

Count = 16000  , Output Voltage = 0.999 V

Count = 24000  , Output Voltage = 2.04 V

Count = 32000  , Output Voltage = 2.04 V

Count = 40000  , Output Voltage = 2.49 V

Count = 48000  , Output Voltage = 4.019 V

Count = 56000  , Output Voltage = 4.007 V

Count = 64000  , Output Voltage = 3.99 V

please provide the appropriate count setting to get full scale output at final count.