Bug fix: Self vergeten in exceptie code

setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = lmwsip
-version = 0.9.9
+version = 0.9.10
 author = Marcel Nijenhof
 author_email = pypi@marceln.org
 description = Interface for the lmw sip protocol

src/lmwsip/__init__.py

@@ -12,7 +12,7 @@ from datetime import datetime, timedelta
 from dateutil import tz
 
 """ Version info changed by git hook """
-__version__ = '0.9.9'
+__version__ = '0.9.10'
 
 class LmwSip:
     """Class to connect to the LMW Standard Interface prototcol (sip)
@@ -1120,4 +1120,4 @@ class LmwParmWarn(Warning):
         self.parameter = parameter
 
     def __str__(self):
-        return("Unknown parameter: %s" % parameter)
+        return("Unknown parameter: %s" % self.parameter)