You are simply compiling an x86 EMGU library to x64 architecture. Go to your project settings properties.... Menu item Project>"Solution name" properties or right clisk on your project file in solution explorer and select properties.
A new window will open with a ribbon bar on the left. Select the build tab and change the dropdown Platform Target: box to x86 also check the Platform: target at the top of this panel.
If you need more help at setting up EMGU have a look at this article:http://www.codeproject.com/KB/cs/EMGU_I ... ssing.aspx
Hope this helps,