Device Driver - failed to open

Hi,

I am new to developing Linux device drivers.
I have written a virtual device driver (char driver). After inserting its module (by insmod) I can see it in the /dev directory.
However, in my application when I try to open the device using "open", it returns -1. The returned errno is 6 (ENXIO).

Am I missing something?
Any help will be appreciated.

Regards,
Mickey

Post your code here for the initialization of the library as well as for the open command.