Improper placement of a comma
Solution 1:
One (and perhaps the original) usage of the comma is to indicate a pause in speech.
Consider the following:
"Skye will become a doctor [pause] and a priest if he finishes theology school."
versus
"Skye will become a doctor and a priest [pause] if he finishes theology school."
These clearly have different meanings. The [pause] can be replaced by a comma.