Hello Rawan,
Your Assembly looks correct but you must find the NPP via the rail settings.
In this shot you have it positioned at 20mm and if this is where you had it when shooting your panorama you gave the download link to, this is not the correct position.
You should take a panorama set at each 1mm increment and stitch to see where the best result comes. The best way to find the NPP with a guide is to use "The Grid" method. As this method gives you a visual guide.
Regards, Smooth