AD9739 harmonics is larger

Dear Sir/Madam,

Currently , I do an experiment with  AD9739a-fmc-ebz-revC eval board and xilinx KC 705 FPGA platform, but when measuring the DAC output signal , I found highr harmonics .Startup initialization is similar to recommended at page 62(Data Sheet AD9737A/AD9739A).I've generated sine wave at 250 MHz and was unpleasantly suprised by the level of harmonics, the actual wave figure please see attached pictures. What could be wrong?