Macanatomist says:

Friday my iPod nano was out of battery :(
I ran 7km, so I decided to create a file with nikeplusedit and to upload it (already made, my nano is dying).
The iPod "sees" the edited run, but when I try to upload it by iTunes it pops up a message of error with the server of the nike site.

Any clues?

Thanks!

 Chris says:

I can't speak on behalf of the Nike site, but I can tell you that R+ also does not accept run data edited by nikeplusedit for the simple fact that it does not produce valid data. I would suggest using something different.

 Macanatomist says:

I made it!
It was the so-well-know bug of the "&".
If your playlist or powersong have the symbol "&" your data will be refused.
Just change it manually and everything will be fine