Solution of the SIR Model (with Birth and Death Rates) of the Spread of a Disease

Traceback (most recent call last): File "/Library/WebServer/CGI-Executables/DiseaseSIRwBD.cgi", line 142, in runsolver(form) File "/Library/WebServer/CGI-Executables/DiseaseSIRwBD.cgi", line 26, in runsolver b = form['b'].value File "/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/cgi.py", line 558, in __getitem__ raise KeyError, key KeyError: 'b'