OS X Lion will not download

I have an older model Macbook that needed the operating system upgraded from Leopard to Lion so I could back up my data to transfer the information to a newer MacBook Pro. Apple advised I needed to oder and install Snow Leopard Disc which I did. I then ordered Lion and I see it in the App Store in Purchases. I hit the grey DOWNLOAD and it responds by turning light grey and then returning to original grey. I was asked for my Apple ID and PW but upon entering there is no change. I does not download or show the download progress bar. I turned the machine off and rebooted to no avail. Apple verified my serial number and processor capability and confirmed the machine can upgrade operating systems,