robust Mahalanobis distances, reverting to robust leverages

Question

I would like to know what to do with the following:

In robMD(x = if (!is.null(x[["x"]])) x$x else if (!is.null(x[["model"]])) model.matrix(x, : Failed to compute robust Mahalanobis distances, reverting to robust leverages.

I tried to use lmrob from robustbase but I am not sure how to proceed

thanks