formatting correct string

Hi There,

I'm experiencing a odd problem while formatting a correct string using
the sprintf object.
I'm trying compile a list of symbols that should look like this:
00:01:14:05. As a SMPTE formatted timecode.

My problem is that I end up with something that looks like this:
00:01:14:5 , so without the last zero.
If someone could point me to the problem I would appreciate it.
here's an example:

Cheers,

Martijn