What could be wrong with this formula please? It is not throwing an error, just evaluating to zero. However, the basic data which I have should return a positive number. The formula is

=SUMIF($C2:$C54,">date(2005,9,30)",E2:E54)

The range c2:c54 contains valid dates some of which are greater than sep 30 2005. The range e2:e54 contains amounts.
The range c2:c54 also includes a few blank cells.