error when Import data Item master from Excel Add-in to AX2012 " ... Object reference not set to an instance of an object"

Hi all,

I have Office excel 2007 SP3 and Ms.Dynamics AX2012 R2 on my machine

I am trying to import some data to EcoResProduct, EcoResproductDimensiongroupproduct, EcoResproductidentifier and Inventtable, but when i go to Publish some data iv got an error like this

"An error occured. The data in the workbook and the behavior of any add-ins may not be correct.

Consider contacting your system administrator about this problem."

"Object reference not set to an instance of an object".

then i go to google and search for the solution :) . i found a page which is discussed about how to import Item/Product to AX2012 through Excell add-ins,http://ax2012exceldataimport.blogspot.com/2012/01/dynamics-ax-2012-products-import-using.html

seems this page have same steps with me on how to import data product/item through Excel add-ins ... but  unfortunatly its not working for me :(

Any suggestion ?? ..

Thanks For ur Help.

Regard

Husna