Try openning up the reports and check out the connection properties in there. The reports are in jbpm-gwt-console-server.war within WEB-INF\classes, they are the rptdesign files and their format is xml.
thenka for the answer.
I checked those files and I found out they were wrong.
I modified them to have the following:
<oda-data-source extensionID="org.eclipse.birt.report.data.oda.jdbc" name="MySQL Local" id="6">
but the problem still happens.