Help with Mitsubishi CP9550DW Printer

[tekatoo]

Our church has the Mitsubishi CP9550DW printer. I'm in charge of developing pictures for an up-coming event (day after tomorrow). I downloaded the printer driver for this printer and I'm trying to print 4X6 pictures (practicing before the real thing). I have the 10X15 (print size) paper/ink loaded, but I keep getting the error that ink and paper are not correct.... I set printer preferences to 4X6 and I tried both portrait and landscape.... when I "feed/cut" the paper, it's actually cutting sheet that are an exact square instead of the 4X6. ANY assistance is appreciated