Firstly, how did you generate the ctl file for wrf output? Basically, you can do it manually by knowing the dimensions and variables list after dumping the wrfout files (i.e. using ncdump). "Blank plot" on GrADS could be caused by many things. I suggest you to use ARWpost or UPP for post-processing if you want to generate GrADS file from the wrfout files.
Thank you and sorry for late Arun Aravind , Ardhi Adhary Arbain . But I generated ctl file using ARWpost then only its giving blank plots, but same wrf ouput is giving me plots in NCL.