AskoR - RNAseq Analysis - GO Enrichment analysis

Hello everybody, i'm using AskoR, package for RNAseq data analysis. I'm performing "GO Enrichment Analysis" using the GOs annotations file to perform enrichment analysis on differentially expressed gene. But when i performed the analysis an error is displayed :
"Contrast: P24vsP0 -> No DE genes with GO annotation!" with all my contrasts.
Do you have any ideas for what could be wrong ?
Thank you !