TPS54116QRTWTQ1 Design| VTT_DIMM and VTERTF Voltage Problem

Hi, guys, I'm new here. Recently I made a design of TPS54116QRTWTQ1 based on the datasheet. According to my design parameters, the actual voltage CPUVCC15 is 1.5V, VTT_DIMM is 0.46V and VTTERF is 0.86V. But the voltages of VTT_DIMM and VTERTF are not correct. When I remove the load behind VTT_DIMM, the voltage is still 0.46V. And I compare mine with the datasheet design, there is no problem as I see. The enable pin controls the switch through CPLD, and the pull-up voltage is 3.3V. The PGOOD pull-up is 3.3V. The voltage on the right side of the test RP6 is only about 2.5V, but it should be 3.3V in theory!!??
Can anybody help me analyze the problem on VTT_DIMM and VTERTF voltage? Thank you!!!!!