After creating a WMS (WMS 1.3.0) in Geoserver (2.15.1) I cannot load the WMS service in Mapbender (v. 3.0.8.1). 
Original WMS-URL:  
http://localhost:8082/geoserver/ows?service=wms&version=1.3.0&request=GetCapabilities  
In Geoserver all of the layers are displayed correctly. The WMS-layers can also be loaded properly in QGIS (WMS-layer).
For the app configuration I have followed the instructions from the [Mapbender documentation][1]. Independently on the chosen source in the layersets of the app the WMS cannot be loaded. I also get the errors: **"element: a target element is not defined"** although I have defined those elements:
[![enter image description here][2]][2]

I also tried to choose other sources which are already available from the source list in Mapbender but got the same errors. I am running both Geoserver and Mapbender on the OsGeoLive13 virtual machine (virtual box). Can someone tell me why the WMS-layers cannot be loaded or why do I see just an empty screen? I simply cannot load any WMS layer in Mapbender but have followed all steps in Mapbender docu. A problem with the getCapabilities document could be the clue. Thank you in advance for your help!

  [1]: https://doc.mapbender.org/en/quickstart.html
  [2]: https://i.sstatic.net/p9mmw.png