There are a number of things that could cause this including the method you used to convert them from color (I'm assuming they were shot in color) to black & white, or that your printer doesn't do black & white well. I say that based fully on things I've read & not from experience because the only black & white I've done was from film in a darkroom. The fastest way to isolate which is causing it is to get one of your photos (that you've printed) printed at a commercial shop to see how it looks. If it's got the colorcast it's not your printer but the file you created. If it prints correctly then it's a printer / paper related issue. Because a lot of people don't understand the full relationship between the taking of a photo, looking at it on a monitor & then manipulating it using an editing program with their monitor at maximum brightness there are a lot of bad files being sent to a printer which then come out wrong relative to the image on screen. I recommend you read this as well as get a print done at a store.
http://photography-on-the.net/forum/showthread.php?t=1132002
Calibrating a quality monitor to match a printer's output is very important to the final outcome but very few have a clue as to what it even means.
"A skill is developed through constant practice with a passion to improve, not bought."
