YR,
I will assume that you have a Planning strategy that is supposed to generate Sales Document requirements (Deliveries are actually Sales documents, even when they are deliveries against a Stock Transport Order).
First check your ECC config. Examine your delivery, VL03N. Find the Item Category of the Delivery item(s).
Now, find the requirements type assigned to this item category. This is typically found in OVZI.
Now that you have the requirements type, find the requirements class. OVZH.
Now that you have the requirements class, examine it. OVZG. You will want to see the setting for "Req. Transfer". If this is un-checked, the material will not appear in MD04. If you check it, then the next delivery you create should appear in MD04.
USUALLY, when the delivery appears in MD04, then it also appears in //RRP3 in APO.
Best Regards,
DB49