In Aperture Assistant 1.0.60 and earlier, {CapDD} isn't adding a leading zero to single figures, so it returns '1' instead of '01'. This is already fixed in the code ready for the next release.
Thanks to Wolfram for reporting this.
Ian
Panoramic photography + software development = lack of sleep.
Also from Wolfram, use a Decision Node and if the Capture Day of Month is less than 10, add in a '0' in the Text Node.
Ian
This should be fixed in version 1.0.61:
http://aperture-assistant.com/betas
Ian