[pvrusb2] Permission denied writing to cur_val

[Larry on the Dell]

My happauge PVR-USB2 wants to default to television input rather than my 
preferred s-video.  So I read cur_val could be written to control this.  
So working my in

lj at mythtv:/sys/class/pvrusb2/sn-8504958/ctl_input$ cd 
/sys/class/pvrusb2/sn-8504958/ctl_input
lj at mythtv:/sys/class/pvrusb2/sn-8504958/ctl_input$ ls -al
total 0
drwxr-xr-x  2 root root    0 2008-10-21 12:35 .
drwxr-xr-x 56 root root    0 2008-10-21 12:33 ..
-rw-rw-r--  1 root root 4096 2008-10-21 12:35 cur_val
-r--r--r--  1 root root 4096 2008-10-21 12:35 enum_val
-r--r--r--  1 root root 4096 2008-10-21 12:35 name
-r--r--r--  1 root root 4096 2008-10-21 12:35 type

lj at mythtv:/sys/class/pvrusb2/sn-8504958/ctl_input$ cat cur_val
television

so I don't want the television input, I want the s-video input.  So 
attempt to write that

lj at mythtv:/sys/class/pvrusb2/sn-8504958/ctl_input$ echo s-video > cur_val

which results in

-bash: cur_val: Permission denied

so I tried

lj at mythtv:/sys/class/pvrusb2/sn-8504958/ctl_input$  sudo  echo s-video > 
cur_val

with the same result. 

-bash: cur_val: Permission denied

This is with  mythbuntu and
MythTV Version   : 18207
MythTV Branch    : branches/release-0-21-fixes
Library API      : 0.21.20080304-1


 From the command line,  how do I set  ctl_imput  to s-video?

Thank you,

Larry Jones