Klen

I using advanced tracking from some sponsors,where you can add values like at this url:
sponsor.com/something?value=1 for advanced tracking purposes.

But,for some reason,a certain number of sent clicks loses content after ?,so sponsor tracking system is
recording it just with sponsor.com/something and then i have no idea for certain number of traffic to what campaign it belong.Any idea why is that happening?
I use simple header redirect like this:
header("Location: sponsor.com/something?value=1");