Printing Reports: Force A4 Format

hello!

i am having trouble forcing a report to be in the A4 format when
sending to the printer. it happens all the time that the report get
send with the format 'letter' which causes the printer to stop and
request for paper in letter format. the report i generate totally fits
in the A4 format but it won't work the way i want it to! this is
pretty annoying because i always have to manually push a button on the
printer so that the report can be printed. is there a way through any
preferences or vba code to make this work ?

maybe someone can help me or give me a hint. thanks in advance!

best regards christoph