WEBENCH® Tools/LM27402SQEVAL: LM27402SQ Circuit Output Fail Problem

Tool/software: WEBENCH® Design Tools

HI

I having trouble using the LM27402SQ/NOPB(WQFN Type)

I built a circuit to get 12V/4A output with 19V input. but It was fail.

I used TI Webench as a reference circuit, and the information is as follows.

When VDD is measured, a 0.7 V sawtooth waveform is output. I would like help.