I have a little confusion while running DESeq2 (I have 2 conditions and three biological replicates). some genes display NA for p and p adjusted even though other values such as base mean and log2 fold change are all given. When I run DESeq on the same sample I get a p value rounded to zero for the same genes with NA with DESeq2. Can you please explain me the reason behind this variation? how can I fix it?