diff -r 5e6d0969bb5d -r 9623d591efb9 plcopen/plcopen.py
--- a/plcopen/plcopen.py	Thu Jun 06 23:01:15 2013 +0200
+++ b/plcopen/plcopen.py	Thu Jun 06 23:45:39 2013 +0200
@@ -1884,7 +1884,7 @@
     
     def removecontentInstance(self, id):
         if self.content["name"] in ["LD","FBD","SFC"]:
-            element = self.instances_dict.get(id, None)
+            element = self.instances_dict.pop(id, None)
             if element is not None:
                 self.content["value"].getcontent().remove(element)
             else: