CAML query not working with dates no idea why

I have startdate as 18/12/2014 and enddate as 22/12/2014 But when trying to use the below query it doesn't work

 <Where>
  <Or>
     <Geq>
        <FieldRef Name='StartDate' />
        <Value Type='DateTime'>
           <Today Offset='7' />
        </Value>
     </Geq>
     <Leq>
        <FieldRef Name='EndDate' />
        <Value Type='DateTime'>
           <Today Offset='-7' />
        </Value>
     </Leq>
  </Or>

Thanks in advance. I did wrap a <Query></Query> around it. Thanks I Advance