Honestly, I don't know what you said or did, because I've never been able to get a 6 character PNR from Iberia when I've purchased an AA code share from AA. I've been told time and time again all I can get is the 5 character (useless) PNR, even after conferencing in someone from Iberia. The AA website will redirect you to Iberia so you can select seats, but I've found it impossible to truly manage my booking. What makes it problematic, at least for me, is that AA IT has great difficulty pushing over traveler data, such as passport information. This makes it impossible to check-in, because your data doesn't match.

I swore off buying IB as AA code shares for this very reason.