InfoPath Dev

I have found some stuff online for this but im not sure I understand it. I want to calculate the number of days between 2 date picker boxes into a third field.

InfoPath doesn't provide any built-in way to calculate date differences in a straightforward manner. There is a somewhat convoluted way to do it codelessly:

http://alecpojidaev.wordpress.com/2008/12/30/infopath-codeless-programming-walkthrough-2/

The other option is a code-based approach. qRules provides a way to make use of code-only functionality without actually writing any code. It provides a DateDiff command, which would be just right for this, along with a multitude of other functionality. I recommend checking it out.

Ok I have tried many times I used the codeless programming from the bizsupport online all it ever returns is 0 for the diffrence. http://www.bizsupportonline.net/infopath2007/calculate-date-difference-infopath-rules-formulas.htm