ORA-error 01858 in asp.net query

[nicks60610]

I keep seeing this error when I run this query and I know the error points to this part of the query:

AND TO_DATE(EQ_EVENTS.EVENT_END_DATE, 'MM/DD/YYYY') = TO_DATE(SYSDATE-24 , 'MM/DD/YYYY')

This is the complete error:

ORA-01858: a non-numeric character was found where a numeric was expected

I checked the database and all dates in this column are listed as 3/27/2006 etc, etc.

What am I missing here?

Thanks!