ORA-21700 when selecting SYSDATE in join with remote table

When I do
SELECT SYSDATE,A.ILH_PRD_ID
FROM INV_LINE_HIST@DB.REMOTE ILH
JOIN PRODUCTS@DB.REMOTE P ON ILH.ILH_PRD_ID = P.PRD_ID;

I get ORA-21700.
When I remove sysdate or the join all works fine. Where can be a problem?

OK:
SELECT ILH.ILH_PRD_ID
FROM INVENTORY_LINE_HIST@DB.REMOTE ILH
JOIN PRODUCTS@DB.REMOTE P ON ILH.ILH_PRD_ID = P.PRD_ID;

OK:
SELECT SYSDATE,ILH.ILH_PRD_ID
FROM INVENTORY_LINE_HIST@DB.REMOTE ILH;

OK:
SELECT SYSDATE,p.prd_id
FROM PRODUCTS@DB.REMOTE P;