The answer James R sent has good information for troubleshooting your range.
When the oven burner lights the flame absorbs the voltage from the spark ignitor. The flame converts the voltage to dc and transfers it into the frame of the range. The dc voltage travels through the frame of the range to the spark module which is mounted in the control panel beside the clock. If the ignition module doesn't receive this dc voltage within 4 seconds after the burner lights, it turns the burner off.
You should inspect the burner and spark ignitor to be sure the flame is burning on the spark ignitor when the bake burner lights. You can watch how the broil burner works and see how the bake burner should work.
Be sure the screws mounting the bake burner to the range are tight. Be sure the holes in the bake burner haven't burned out and are producing a lazy flame around the ignitor.
If you have more questions, reply on this thread and I will be glad to help.