Queue number not generated in TO

I am trying to create a TO using LT03 from an outbound delivery document. Here TO is getting created, but Queue number is not getting created. Can someone tell me what might be the reason for Queue not getting genaretd for TO.

As I am new to WM, plz tell me what all are the basic configurations, we should check related to queue number generations. The created TO is not yet confirmed.

Thanks

Vineeth Varghese