[BioC] reading background from imagene output

[marchiem at libero.it]

Hello everybody,
I've noticed that read.maimages doesn't read the same type of value for the signal and the background. If I'm not wrong Imagene output file has three values for them(mean,median and mode); apparently by default read.maimages takes the mean for the signal and the median for the background...
For example, how can I extract the median signal and the median background?
I tried not to use the parameters source="imagene" and I've defined the columns of desired values:

>RG<-read.maimages(files,R="Signal Mean",Rb="Background Mean",G="Signal Mean",Gb="Background mean")

but I got this message:

Error in read.maimages(files, R = "Signal Mean", Rb = "Background Mean",  : 
        Cannot find column heading in image output file

please somebody help me out!
sorry if once again I bother You with my basic questions...
Thanks in advance.

Emanuele