# Why is ferret giving me error that the region is not 2D while plotting

I have downloaded ERA5 data and am trying to plot temperature variable. The problem I am facing is that even after providing a 2D area for plotting, ferret is giving an error saying that the region must be 2D

yes? fill t[k=1,l=1]
**ERROR: dimensions improperly specified: must be a 2D region
CONTOUR/FILL t[k=1,l=1]


yes? fill 't'[k=1,l=1]