Problems with adding a sysfs file

I followed this link to add a sysfs file http://kroah.com/log/blog/2013/06/26/how-to-create-a-sysfs-file-correctly/ . I set the driver.groups field and declared the attribute and attribute groups required by the sysfs file. When I boot my kernel I see the file but my store and show handlers don't get called when I try to cat or echo to the file. Is there any step I'm missing ?. I also see that a lot of drivers still use sysfs_create_file which is racy according to the link I posted. - AB