Cannot restore pre-installed Office 2010 after installing new Hard disk

I have a Dell Vostro 230 that came with pre-installed Office 2010 Home and Business. I tried to download the Office 2010 from Microsoft web-site after I changed the hard disk.

But there was an error message:

"The product key you entered appears to be for software pre-installed by the device manufacturer. Please contact the device manufacturer for software recovery options."

But Dell gave the link: products.office.com/.../download-back-up-restore-microsoft-office-products

The Office 2010 product key is a sticker attached on the top of my computer.

It is not that I do not have the product key. The whole problem is that Microsoft asked me to contact Dell but Dell direct me to Microsoft. 

What should I do next? Please help. Thank you.