Possibly related to issues reported here:
http://developer.atlassian.com/jira/browse/JCHART-12

The following two macros does not show anything on the confluence page:

{jiraportlet:url=http://jira.objectware.no/jira/secure/RunPortlet.jspa?portletKey=com.atlassian.jira.ext.charting:createdvsresolved&cumulative=true&daysprevious=30&periodName=daily&projectOrFilterId=filter-10559&versionLabels=major&os_username=XXX&os_password=XXX} {jiraportlet:url=http://jira.objectware.no/jira/secure/RunPortlet.jspa?portletKey=com.laughingpanda.jira:versionWorkloadChart&chart.height=300&chart.width=500&startDate=2006-01-01&versionId=10418&os_username=XXX&os_password=XXX}

Both works just fine in JIRA dashboards.

When I alter the url to something invalid the macro evaluates the url to be invalid.

No HTML is rendered from the macro.