strange query results

 I am running to a strange query situation. My database version is 10.2.0.3 with compatible set to 9.2.0.8 and os is solaris 9.

I issue the select query:

select t$item, t$clot from user.dltc900100;

This query returns about 800K rows.

Then I issued the query:

select t$item from user.dltc900100 where t$clot=0302047;

But the query returns no rows selected.

This name has returned from the first query. Why would it not show up from the second query?

I am puzzled. What am I missing here?