module licence unspecified taints kernel

Hi All,
I am trying to create one kernel module that is multi file module .

i am trying to do thi sfor my learning purpose .

when i am trying to compile it its getting compile properly but when i am trying to load it its init function is not getting invoked and while dmesing i am getting msg like

module licence unspecified taints kernel.

while i already defined the module licenece as dual bsd/gpl.

can any body help me in understanding why i am getting this.
i am unable to find any help from google also .

Regards
Nayan