[R] randomForest: tuneRF error

[Dennis]

Just curious if anyone else has got this error before, and if so,
would know what I could do (if anything) to get past it:

> mtry <- tuneRF(training, trainingdata$class, ntreeTry = 500, stepFactor = 2, improve = 0.05, trace = TRUE, plot = TRUE, doBest = FALSE)
mtry = 13  OOB error = 0.62%
Searching left ...
mtry = 7        OOB error = 1.38%
-1.222222 0.05
Searching right ...
mtry = 26       OOB error = 0.24%
0.6111111 0.05
mtry = 52       OOB error = 0.07%
0.7142857 0.05
mtry = 104      OOB error = 0%
1 0.05
mtry = 173      OOB error = 0%
NaN 0.05
Error in if (Improve > improve) { : missing value where TRUE/FALSE
needed


I've used tuneRF successfully before, but in this instance, no matter
what I change in the parameters, I still get the error above (last
line). The data has no NAs in it. I'm using R 2.12.0 (64bit-M$ Windows
7).

Thanks in advance!