problem with the plot.ordination( ) function

[Teo2091]

hello everyone,
i'm trying to plot the ordination results with the plot.ordination() function, but there is a problem in this function. The error is:

Error in names(x) <- value :
'names' attribute [3] must be the same length as the vector [0]

What does this error mean? Before this step (plot.ordination()), i have used the ordination ( ) function, as reported in the workflow, without errors. Can you help me?

Thanks,
Matteo