I have grid which is editable. when I changed the value in particular cell and after that when 

I pressed the Tab key to go to next cell it give me error " Object Refrence not set to a instance ".

This error make me crazy I tried to search inner exception but nothing found.

I have written cell updated event of grid which fired and data saved in database but it give the

this error. This happen only when I pressed tab key after value changed

For all other key like enter or mouse click its work normal.

Please help me on this. Thanks in advance.