LM27402: LM27402 Output Fail Problem

Part Number:LM27402

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 or sine wave is output. I would like help.