Android :: Android Custom Dialog NullPointerException

I cannot for the life of me figure out why I'm getting a NullPointerException.

When a user clicks on a particular image, a dialog window is supposed to pop-up and display a larger version of said image:

CODE:..............

The associated onCreateDialog looks like this:

CODE:.........

For reference, this is cover_dialog.xml:

CODE:....................

Now, when the image previously described is clicked, the application immediately crashes and throws the following error through LogCat:

CODE:......................

The line in question refers to this line inside of onCreateDialog:

coverLarge.setImageBitmap(book.getCover());

I don't get why coverLarge is null at that point.