[R] Error:length of dimnames [2] not equal to array extent ?

[Robin Gruna]

Hi everyone,
I have the following problem:
I want to perform a LDA with the function lda().
My data object mat.data is a matrix with dimensions

> dim(mat.data)
[1] 1228   44

and my grouping vector grp has length 1228:

> length(grp)
[1] 1228

Every time I call lda(), the following error message occurs:

> lda(mat.data,grp)
Error in lda.default(x, grouping, ...) : length of dimnames [2] not equal to
array extent

In order to find the error I created a matrix mat.test

mat.test<-matrix(1:500,nrow=1228,ncol=44)

with arbitrary entries an the same attributes as mat.data:

> dimnames(mat.test)
NULL

> dimnames(mat.data)
NULL

But with the test object mat.test there occurs no error !
Can somebody help me, this really makes me crazy,
thanks,
Robin