MWUMrs find master regulators on original clusters

[TangentDeng]

Hi PISCES team, great work!
When I run

data.obj <- MWUMrs(data.obj,clust.vect = 'cluster')  ##cluster is the original seurat cluster in metadata
[1] "Identifying MRs for cluster cluster"
[1] "WARNING: Group size <30, normal approximation may not be appropriate..."
Error in wilcox.test.default(x[clust.samps], x[ref.samps]) : 
  not enough (non-missing) 'x' observations

How to fix this error?
Thanks!