The second example that you gave is syntactically correct. The colors have to be in double quotes. For some reason, it seems like it's having an issue with the colors that you chose. To verify that, try substituting simpler colors like this:
iif( Fields!ReportRevenue.Value = 1,
"Red", "Blue")
BTW, I was able to use your same colors in a test report, although it was SSRS 2005.
Greg