Problem in calculating formulas in word using open xml

Hi Team,

I am generating a word document using open XML. In my word doc i have formulas like

{=IF(<<MERGEFIELD>> > 100,10,0)}

am able to replace the MERGEFIELD with a value lets suppose 50 and when trying to generate the word document the formula is not updating, it just displays as 

{=IF(50 > 100,10,0)}

rather than 0. The value is not updating

please help me out

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Harish