Hi,

>Where am I going wrong?! I am trying to create topGO object by custom annotations, But am facing difficulty again and again. 

> GOdata <- new("topGOdata", ontology = "BP", allGenes = P_values, geneSelectionFun = topDiffGenes, description = "Simple session", annot = annFUN.gene2GO(whichOnto = "BP", feasibleGenes = NULL, gene2GO), gene2GO = gene2GO)

Building most specific GOs .....
Error in annotationFun(ontology, .Object@allGenes, ...) : 
  could not find function "annotationFun"

>If anyone could give some useful solution on urgent basis, would be highly appreciated. 

Thank you.