新建一个S4方法的问题

<br />
setMethod("heatmap.2", signature(object="clValid"),<br />
          function(object, cellnote=NULL, notecol="black", dendrogram="none",<br />
          	Colv="NA", labCol=NULL, labRow=NULL, main=NULL,<br />
          	method=clusterMethods(object), nClusters=nClusters(object),...) {<br />
          	method <- match.arg(method, clusterMethods(object))<br />
          	nClusters <- match.arg(nClusters, nClusters(object))<br />
            enrichment = enrichment(object, method, nClusters)<br />
          	if (is.null(main)) {<br />
          		main = paste(method, nClusters,"Cluster-Pathway-Enrichment-Analysis")}<br />
          	heatmap.2(enrichment, cellnote=enrichment, notecol="black",<br />
          		dendrogram="none", Colv="NA", labCol=colnames(enrichment),<br />
          		labRow=rownames(enrichment), main=main, method, nClusters)<br />
          })<br />

load_all()时报错：

<br />
Error in setGeneric(f, where = where) :<br />
  must supply a function skeleton for 'heatmap.2', explicitly or via an existing function<br />