[R] topicmodels error

[Dario Solari]

I try to fit a LDA model to a TermDocumentMatrix with the topicmodels
package...
but R says:

> Error in LDA(TDM, k = k, method = "Gibbs", control = list(seed = SEED,  :
> x is of class “TermDocumentMatrix”“simple_triplet_matrix”

> class(TDM)
> [1] "TermDocumentMatrix"    "simple_triplet_matrix"

I try to use a matrix... but don't work:

> MAT <- as.matrix(TDM)
> Error in LDA(MAT, k = k, method = "Gibbs", control = list(seed = SEED,  :
> x is of class “matrix”

The help say is correct to use a DocumentTermMatrix:
> Arguments
> x	 Object of class "DocumentTermMatrix"

Can anyone help me?
Thanks