Fix PayPal Express Checkout payment on Opencart site

Hello people i need to fix PayPal Express Checkout payment on my customized Opencart 1.5.2.1 version based site. I installed this extension and i need to enable PayPal Express payment on my site: [login to view URL] All is working if i pay without PayPal [login to view URL] is going wrong when i try to pay using PayPal account (error Notice: Undefined index: EMAIL). These are my project requirements: 1) Fix PayPal Express payment when user is logged into PayPal account 2) Fix fees calculation for this payment during checkout (add fixed value to fees) PLEASE NOTE THAT I WILL ONLY RELEASE MILESTONE ONLY WHEN BOTH ABOVE POINTS WILL SHOW RESULTS OTHERWISE I WILL NOT PAY. DO NOT ASK TO BE PAYD IF I DO NOT SEE RESULTS AT MY SIDE. DO NOT PLACE BIDS OUT OF BUDGET!!! PLEASE READ CAREFULLY ALL REQUESTS AND POST YOUR BID ONLY IF YOU ARE ABLE TO MANAGE AND COMPLETE THE PROJECT. Payment details : 100% milestone at project start. Milestone release will be completed ONLY when you will get my complete satisfaction.