Please download the correct S0F or recompile - Help?!

Hi,

I am new to the Aletera NIOS II DE0 board. I am setting mine up and trying to run a program on it. But I get the following error:

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The software you are downloading may not run on the system which is currently configured into the device. Please download the correct S0F or recompile

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How can I fix this issue? I have heard that it is easy?

Thanks,

Dan