How should I import data from seurat to scmap?

[jsonProgram]

hello ,Vladimir Kiselev and Martin Hemberg

I got error for this code:

SAMPLE <- Seurat::Read10X("./00_Data/Sample_matrix_10X/")
sce <- SingleCellExperiment::SingleCellExperiment(assays=list(counts= SAMPLE ))
seur <- Seurat::CreateSeuratObject(SAMPLE )
sce <- Seurat::as.SingleCellExperiment(seur)
sce <- scater::logNormCounts(sce)
rowData(sce)$feature_symbol <- rownames(sce)

#Feature selection
sce <- scmap::selectFeatures(sce, suppress_plot = FALSE)

##error
sce <- indexCluster(sce)
Error in scmap::indexCluster(sce) :
Please define an existing cluster column of the colData slot of the input object using the cluster_col parameter!

Thanks a lot!