I want to print custom size page from tray 1 (HP LaserJet 2420n)

Hi

i am using HP Laser jet 2420n, mostly i am using Tray 2 for Printing on A4 Size and thats OK

but when i want to print something in custom size ( Letter PAd etc) from Tray 1, it is not working and Loads paper form Tray 2 Automatically, while i also loaded paper in Tray 1 but fails to Load the paper from Tray 1 for Printing.

your guidance in this regard will highly be appreciated. 

Regards