Using dd comand

Hello peolple i have to check a tape with de dd comand and redirect the exit

dd if=/dev/rmt/0cn ibs=1024k of=/dev/null 

i need that the exit from that commando go to a log
if a do this

dd if=/dev/rmt/0cn ibs=1024k of=/dev/null > x.log 

don`t send me nothing to the log only in the screen. I need to do this so i can run this commando into background.Thank you for your time
�'m running this command into a secure crt window

It's printing to standard error, so try 2> instead of >