Query join

Experts,

I need to join the Sales Order and Purchase Order on a UDF. I get no results with the query below and I think the join is wrong.

SELECT T1."DocNum", T0."DocNum", T1."U_L_02"

FROM ORDR INNER JOIN OPOR T1 ON T0."U_NBS_L_02" = T1."U_NBS_L_02"

WHERE T0."U_L_02" = T1."U_L_02"

Any help would be appreciated,

Marli