Counting no of days between dates

Question

Hi,
 I am working on leave module. we maintain all holidays related dates in holidaydatadase list . when leave is applied the start date and enddate is menctioned . so we need to count no of days between the start and end dates
 - holidays .

 For this i wrote a caml query

<Where><And><Geq><FieldRef Name='holiday'/><Value Type='DateTime'>" +FromDate  + "</Value></Geq><Leq><FieldRef Name='holiday'/><Value Type='DateTime'>" + Todate  + "</Value></Leq></And></Where></Query>"

holiday is a column in holidaydatabase list.

i am getting zero values when this query is executed
can any on help