I am defining an if condition in my jmeter. Whenever there is a variable defined in regular expression extractor contains a value then only the next HTTP request must trigger. But the IF condition is not recognizing and it is not allowing the HTTP to execute.

Thread Group
  Single Controller
    HTTP Request 1
    Regular Expression Extractor
    IF Controller
      HTTP Request 2

Regular Expression Extractor is taking a value "po_atid" from the response body

IF Controller "${po_atid}" != "" && "${po_atid}" != "NOT_FOUND"

But the IF condition is not at all returning true. The HTTP Request 2 is never getting executed even if po_atid is having a proper value.