Duy,
From the scope captures it seems that you are writing data on the rising edges of SCLK. The DAC7716 uses the falling edge of SCLK to latch in the data. Shifting your data by half an SCLK cycle should make it work.
As a side note. If you are planning on using it as a transparent, you can just tie LDAC LOW and the DAC output will update on the 24th falling edge of SCLK. There is not need to pulse LDAC before the frame.
Let me know if this solves your issue.