Color key not shown with heatmap.2

I am not able to display the color key while using heatmap.2. I've read it should appear automatically, is it true? Otherwise I've tried several times but only the heatmap appears.

Here is my code:

heatmap.2(corr_RSEM_immuno,Colv = NA, Rowv = NA,col=my_palette,trace = "none",dendrogram="none",margins = c(5,15), key = T, keysize = 0.5)