Try this
SELECT T0.[OpprId], T0.[Name], T1.[CardName], T2.[Name], T2.[Tel1],
T2.[Cellolar], T2.[E_MailL], T0.[U_OPR_NEXTSTEP], T3.[SlpName]
FROM OOPR T0 INNER JOIN OCRD T1 ON T0.CardCode = T1.CardCode
INNER JOIN OCPR T2 ON T0.CprCode = T2.CntctCode
INNER JOIN OSLP T3 ON T0.SlpCode = T3.SlpCode
WHERE T0.[U_OPR_NEXTSTEP] <= getdate() and T3.[SlpName]=[%1]
--Manish