It sounds like you referenced a parent in your POM. That is, you pom.xml has a <parent> section. If you do that, the parent artifact must be of package type "pom".
Maven supports two different POM hierarchies:
One is the master/subproject hierarchy. In this hierarchy you have a master POM that, when you run a build, will also build submodules. This hierarchy is defined by placing a <modules> entry into the master POM. The mast and submodule POMs can use any packaging type. Example: a master POM with packaging type of "ear" might have submodules of type "jar" (for an EJB project) and "war" (for the web app project).
At work I constantly preach against people confusing the two hierarchies (lost of example on the web mix the two hierarchies thus adding to the confusion). My recommendation is to never use the master/submodule hierarchy - if you need that build it into Jenkins. But use the parent/child relationship everywhere that you can; it significant reduces rework (I wholly support the DRY principle - Don't Repeat Yourself).