Null Reference Exception on FragmentManager.BeginTransaction(). Fragment to Fragment

noahdavidson

Inside of a fragment Im using a gridview to display an infinite list of image Buttons.
Inside the gridView BaseAdapter the Image Button Click call looks like this:
`imgThumbail.Click += (e, o) => {
Toast.MakeText(_context, "Img Button Clicked", ToastLength.Short).Show();

            Fragment fragment = new MyExpandedGridCell();
            FragmentTransaction fragmentTransaction = context.FragmentManager.BeginTransaction();
            fragmentTransaction.Replace(MainActivity.mainFragmentLayout, fragment);
            fragmentTransaction.AddToBackStack(null);
            fragmentTransaction.Commit();
        };`

On line FragmentTransaction fragmentTransaction = context.FragmentManager.BeginTransaction();
Im getting a null reference Exception.

The intended behavior is have the imageButton click replace the current Fragment with another Fragment. Does anyone know why this doesnt work?