Dear useRs,i am applying "mantel test" to find the correlation between distance matrices, by ade4 package. some of the correlations, although given me r-values, have shown following warning message.. "In is.euclid(m2) : Zero distance(s)" i wanted to know that why has this message prompted? although i have got the result but still is it of concern?thanks in advance regardseliza [[alternative HTML version deleted]]