Flash Builder 4.5 Std installation

Hi All,

I bought Flash Builder 4.5 Std in 2010. But I lost distribution package. Where can I download it to install again on my computer? In my products list I do not see download link any more.

I know that Flash Builder 4.5 is free upgrade to 4.6. I have found and downloaded  4.6 from following link "http://www.adobe.com/support/downloads/thankyou.jsp?ftpID=5517&fileID=5536"

But unfortunately when I enter serial number i got "This serial number is not valid for this product"

Please help.

Thanks.