TSQLQuery Multiple Params in Multiple Tables

I'm joining two tables.  I'm setting two parameters.  One parameter for each
table.  If I run the sql in SqlPlus I get the correct records. However, when
I run with TSqlQuery (D6
Update 2 - Oracle 8.1.7 database), I get no records.  I get records if I
just use one parameter.

Is there something special I need to do to set this up, or is this a
limitation?

Thanks
SELECT *

FROM EQUIPMENT, EQUIPMENT_TYPE

WHERE EQUIPMENT.EQUIP_ID = EQUIPMENT_TYPE.EQUIP_ID

AND EQUIPMENT.EQUIP_ID = :EQUIP_ID

AND EQUIPMENT_TYPE.EQUIP_CODE = :EQUIP_CODE