[R] Cryptic error message from rfe (in caret package)

[Richard R. Liu]

When using the function rfe I receive the warning

In x == y : longer object length is not a multiple of shorter object  
length

more than 50 times.

I call rfe as follows:

nbProfile <- rfe(features.train.50pct, truth.train.50pct, sizes =  
no.features, rfeControl = nbCtrl)

where
features.train.50pct	data frame of 8 named columns, each of 487 rows,  
numeric
truth.train.50pct	factor of 487 logical elements
sizes			1, 2, ..., 8
nbCtrl			rfeControl(functions = nbFuncs, method = "cv", verbose = F,  
returnResamp = "final")

Does anybody know to which objects the warnings refer?

Richard R. Liu
Dittingerstr. 33
CH-4053 Basel
Switzerland

Tel.:  +41 61 331 10 47
Mobil: +41 79 708 67 66
Email:  richard.liu at pueo-owl.ch