rrdtool create using python in Ubuntu 10.04 raises "TypeError: argument 3 must be string"

I was trying example 2 from this page: http://oss.oetiker.ch/rrdtool/prog/rrdpython.en.html#___top

It was working perfectly for me in Ubuntu12.04 but when I tried to port my code to Ubuntu 10.04, I got the following error:
Traceback (most recent call last):
  File "test.py.orig", line 14, in
    'RRA:AVERAGE:0.5:6:10' )
TypeError: argument 5 must be string

Wasted a lot of time trying to solve it before this finally worked:

rrdtool.create( 'speed.rrd',

              '--start', '920804400',

      '-s', '60',

              'DS:speed1:COUNTER:600:U:U',

              'DS:speed2:COUNTER:600:U:U',

              'DS:speed3:COUNTER:600:U:U',

              'RRA:AVERAGE:0.5:1:24',

              'RRA:AVERAGE:0.5:6:10' )

Hopefully, it saves someone a bit of time