PageMethods is undefined

Hi,

I am calling a web service from client side using Ajax ScriptManager & by using javascript PageMethods object to call the web service

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[I get javascript error "PageMethods is Undefined"]

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code as below

function a()

{

bEligible = PageMethods.FPLEligibility(famSize, grossAnnual, meansTest, OnComplete, OnError);

 }

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<asp:ScriptManager Go to the complete details ...