Create synonym

Hi,

On 11.2.0.4

I connected to DB as  USER1 and created a synonym:

CREATE OR REPLACE SYNONYM USER1.TAB1 FOR USER2.TAB1;

But other users (USER4, 5,6) can not use this synonym. Only USER1 can use it.

Whet to do for USER4, 5, 6 can use it also ?

Thanks.

PS: USER1 has grant: SELECT on USER2.TAB1