KML Export Wizard does not work

When trying to export a feature layer to kml, I run into these issues:

• if I try to enter a filename in the wizard screen (cfr attachment), I cannot enter any text
• if I create an empty .kml file, I can select it (using the ... button), but when exporting a WFS or WMS layer, I get this error:

java.io.IOException: The selected resource is not a feature layer: fietsknooppunten
at eu.udig.tools.jgrass.kml.wizard.KmlExportWizard$1.run(KmlExportWizard.java:109)
at net.refractions.udig.ui.PlatformGIS$3$2$1.run(PlatformGIS.java:389)
at net.refractions.udig.ui.PlatformGIS$1.call(PlatformGIS.java:111)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:680)

• if I first export the layer to a shapefile and then try to export to kml, I get no errors, but the .kml file remains empty.