Null references Exception whice generating a word document

Hi,
I am using aspose.word with asp.net using c#. I have a word template that user can download. I am using mail merge to add some data in the template. When i do it with a regular A4(8.5X11) size document it is working fine. But when i used a different size(14X8.5) , it was throwing this exception. The template also had some textbox fields which is used to display the mail merge data. Is there something else that i need to do, if i want to add data in textbox of the template.
It throws this exception on following line of code:

Document doc = word.Open(MapPath(“.”) + “\…\Documents\Approved_Document.doc”);

I appreciate your help.Thank you.

- Vinay

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