Hi, I can't outline the shekel sigh, and when using Flatten Transparency option instead it gives this error. There are no spot colors in the artwork.
Really impossible to know without any actual info about your document. Still possible that you unwittingly used soem Pantone swartches or whatever and haven't converted them yet, so the message may not be a fluke at all. either way, you have to be more specific and provide soem details.
Did you check Window > Separations Preview for spot colors?
If there are hidden spot colors, clicking Overprint Preview in the Separations Preview panel should give you a warning too.
I face the same problem. There aren't any CMYK colors in the separation preview window; the color is cmyk not a pantone, spot color one.