DAC38J84: DAC38J84: LMFS：4221 No Output,Serdes PLL can not Locked

Configure other modes such as LMFS8411 2x interpolation， LMFS4221 4x interpolation；DAC38J84  have output normal。

But  Mode 4221,sample clcok =1.2GHz, 2x interpolation, 4 lan.

the lan rate should be 12Gbaud,sample clock is external and CLOCK_PLL is power down.

k=32,    SYSREF=2.34375MHz

Register configuration sequence；JESD204B  link is normal ，But DAC38J84 no output？  Why？

24'h1A_0020
24'h1B_0000
24'h31_1000
24'h32_0000
24'h33_0000
24'h3B_0800
24'h3C_0028
24'h3D_0088
24'h3E_0108
24'h3F_0000
24'h46_1882
24'h47_01C8
24'h48_3143
24'h49_5500
24'h5F_3210
24'h60_5764
24'h24_0020
24'h25_2000
24'h00_0118
24'h01_00F3
24'h02_2082
24'h03_F300
24'h04_F0F0
24'h05_FF07
24'h06_FFFF
24'h07_3100
24'h08_0000
24'h09_0000
24'h0A_0000
24'h0B_0000
24'h0C_0400
24'h0D_0400
24'h0E_0400
24'h0F_0400
24'h10_0000
24'h11_0000
24'h12_0000
24'h13_0000
24'h14_0000
24'h15_0000
24'h16_0000
24'h17_0000
24'h18_0000
24'h19_0000
24'h1E_9999
24'h1F_9980
24'h20_8008
24'h22_1B1B
24'h23_0100
24'h26_0000
24'h2D_0001
24'h2E_FFFF
24'h2F_0004
24'h30_0000
24'h34_0000
24'h4A_0F1E
24'h4B_0801
24'h4C_1F03
24'h4D_0300
24'h4E_0F2F
24'h4F_1C61
24'h50_0000
24'h51_00DC
24'h52_00FF
24'h53_0000
24'h54_00FC
24'h55_00FF
24'h56_0000
24'h57_00FF
24'h58_00FF
24'h59_0000
24'h5A_00FF
24'h5B_00FF
24'h5C_1133
24'h5E_0000
24'h61_0111
24'h64_0000
24'h65_0000
24'h66_0000
24'h67_0000
24'h68_0000
24'h69_0000
24'h6A_0000
24'h6B_0000
24'h6C_0002
24'h4A_0F1E
24'h4A_0F1F
24'h4A_0F01
24'h03_F301