grant privilege to another user

I am logging into oracle as a simple user.I want other user who are logged in to the same database as i am ,be able to see and manipulate tabels and stored procedure. I used grant privilege to achieve this.

        grant  all on tablename to user;

but it is not working ie on querying the table it is showing no such table or view exists. Ho开发者_StackOverflow中文版w should i achieve this.

The other user may have to use a schema name when accessing the table. eg. select * from user1.table1