I am having an aweful time trying to do something that should be simple

add a dynamic amount to a html hidden input.
this is my latest attempt. 
.aspx
<input id="ppamount" type="hidden" runat="server" />
in the page load
ppamount.Attributes.Add("name", "amount") 
ppamount.Attributes.Add("value", "9.99")
Please help me out.  i have done my research but still confused. 
i hard code it in the html fine but not from code behind.  
 
thanks for you help!
 
 

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