[R] error using predict() / "fRegression"-package

[Gero Schwenk]

Hello!
I'm puzzled by the following problem. It occurs while trying to predict 
responses in a test-dataset using a linear model fitted with regFit from 
the rMetrics "fRegression"-package.

All goes well when I call "predict" using the training dataset. However, 
a call using the test-dataset retuns an error message - telling me that 
the latter dataset provides variables of different type than the 
training set. But inspection of the structure of both dataframes shows, 
that the variables are still all of the type "numeric". (See attached 
session protocol.)

Does anyone have an idea how to fix this? Any help would greatly be 
appreciated!
Kind regards,
Gero

 > str(regdata)
'data.frame':    89 obs. of  7 variables:
$ ret1                 : num  0.0275 -0.01013 0.00569 -0.01582 0.0226 ...
$ lag(ret1)            : num  NA 0.0275 -0.01013 0.00569 -0.01582 ...
$ lag(ret2)            : num  NA 0.04072 -0.00509 0.02055 -0.01548 ...
$ lag(ret3)            : num  NA 0.05393 0.00299 0.02432 0.02251 ...
$ (lag(ret1)*lag(ret2)): num  NA 1.12e-03 5.16e-05 1.17e-04 2.45e-04 ...
$ (lag(ret1)*lag(ret3)): num  NA 1.48e-03 -3.03e-05 1.38e-04 -3.56e-04 ...
$ (lag(ret2)*lag(ret3)): num  NA 2.20e-03 -1.52e-05 5.00e-04 -3.48e-04 ...
 > str(regdata.test)
'data.frame':    23 obs. of  6 variables:
$ lag(ret1)            : num  NA 0.01554 0.01458 0.00333 0.01674 ...
$ lag(ret2)            : num  NA 0.01373 0 0.01331 0.00686 ...
$ lag(ret3)            : num  NA 0.0278 0.0152 0.0211 -0.0104 ...
$ (lag(ret1)*lag(ret2)): num  NA 2.13e-04 0.00 4.43e-05 1.15e-04 ...
$ (lag(ret1)*lag(ret3)): num  NA 4.32e-04 2.21e-04 7.03e-05 -1.75e-04 ...
$ (lag(ret2)*lag(ret3)): num  NA 3.82e-04 0.00 2.81e-04 -7.16e-05 ...
 > ar1.xpred.fitted <- regFit(ar1.xpred.model, data = regdata, use = "lm")
 > ar1.xpred.train.pred <- predict(ar1.xpred.fitted, regdata, se.fit = 
FALSE)
 > ar1.xpred.test.pred <- predict(ar1.xpred.fitted, regdata.test, se.fit 
= FALSE)
Fehler: variable 'lag(ret1)' was fitted with type "numeric" but type 
"nmatrix.1" was supplied
Zusätzlich: Warnmeldung:
'newdata' had 23 rows but variable(s) found have 89 rows
 >