Jenkins Script: Trigger using Shell not working

Question

I am using Jenkins script polling.

• [ScriptTrigger] - Poll with a shell or batch script IS CHECKED

• script value is

  #!/bin/ksh
  return 0 
  

• Exit Code PARAMETER IS 0

• polling Schedule is * * * * *

The polling is never happening and the build run only if i schedule a build manually .

What am i doing wrong? What should i change?

The script trigger log is

[ScriptTrigger] - Poll with a shell or batch script

Polling has not run yet.