Xeta
Are you referring to P5 or the Canvas API?
Best help I can offer is to check that it's spelled correctly, no errors occur before this command executes, and that the arguments in the command are valid. Also check your CSS and make sure the element you're drawing on is fully visible.
Actually, feel free to reply with a link to your project if you'd like me to see for myself, I've got a few years of eperience (and no certificate to show for it XD)