Cannot view prices to upgrade

I currently have 4 lines, 3 with on an installment plan. I preordered the iPhone 6 Plus as an upgrade to a line where I had a tablet, but do the backorder I cancelled it and went to a store and got the regular iPhone 6 and upgraded another line and used the trade-in program to pay off the installment on the tablet. Now when I attempt to see about upgrading, it is showing I would have to pay $949.99 (price of the iPhone 6 Plus) to upgrade the tablet.

When I attempt to look at another line, it will give me the option to pay $108.75 which is the remainder of the 12 months on the Next or pay $398.74 to pay it in full. After continuing to the online store it would state "To upgrade now, you'll just need to pay the remaining balance of your initial 12 or 18 installments and trade in your qualifying device. Or, upgrade without a trade-in by paying off all the remaining installment payments." Whenever I add an item to the cart, it would state:

You’re Not Eligible for a Trade In

Unfortunately, you’re not eligible to trade in your device.
You can do any of the following:

• Pay off your installment plan with AT&T. To do so, choose Pay Off Device.
• Stay on your current installment plan with AT&T.
• Locate an AT&T retail store near you to discuss your trade-in options. Click Find my store to open the AT&T Maps page.