|My magnolia tree is over 5 years old and has not produced a flower.|
|You didn't give the variety of your magnolia, but some are very early spring bloomers and their flower buds are easily damaged by cold winter weather and late spring frosts. Watch your plant this autumn and winter to see if it develops flower buds at the ends of the branches. I'll bet you'll see them develop but then die off in a late frost.
If this is the case, you might want to move your tree to a more protected spot in your garden to improve its chances of producing flowers each year.