Hello there! I'm using this component in order to get 5V at the output, using a Vin of 20V. The schematic is the following:

where SHDN is floating, not like the schematic shows. L2 is 22uH, C11 is 100uF and there is a schottky diode in SW pin to GND (not shown in the schematic). As I tell, Vin is 20 Volts, and the resistances are chosen to get a 5V output, but I'm not getting the output.
If I catch the Diode signal with the oscilloscope, I get the following signal, which is really weird:

Does anyone know where the issue can be?
thank you very much!