[BioC] question about the error from function intraspotCorrelation

[Ren Na]

I tried to do individual channel analysis of two-colour microarray data.
I sort of followed the example in function lmscFit. When I ran to the
the following step, I got the error,
corfit <- intraspotCorrelation(MA, design)
Error in if (dev < devold - 1e-15) break :
        missing value where TRUE/FALSE needed

I checked M and A, there is no missing value. Does anyone know what
cause this error? 
Thank you very much.