2010 Mac Pro won't install Mavericks?

I have a Mac Pro Core 8 that I purchased directly from the Apple website in 2010. However, I'm told that I can't upgrade to Mavericks because my computer is too old.

The information on the Apple website says that it should work on Mac Pro's from 2008.

So what gives?

Any info appreciated ( ie, is there a way to see the actual manufacture date using the serial number?)

Hardware Overview:

Model Name: Mac Pro

Model Identifier: MacPro2,1

Processor Name: Quad-Core Intel Xeon

Processor Speed: 3 GHz

Number of Processors: 2

Total Number of Cores: 8

L2 Cache (per Processor): 8 MB

Memory: 10 GB

Bus Speed: 1.33 GHz

Boot ROM Version: MP21.007F.B08

SMC Version (system): 1.15f3

Serial Number (system): 40******0GP

Hardware UUID: 00000000-0000-1000-8000-001D4F4514E8

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