Can't Create Table .no Permission?

question 1 :
I create a login account and a user account ,and then grant create table permission to the user.
But the user can't create table yet,it return a error message:
The specified schema name "dbo" either does not exist or you do not have permission to use it


But i can find the dbo scheam by querying sys.schemas.

the sql script i execute:

(sa login)



Code Snippet
use tempdb
go
create login l1 with password='a' ,check_policy=off
go
create user u1 for login l1
go
grant create table to u1





Code Snippet
(l1 login)
use tempdb
create table table1
(
col int
)


--fail
--error message:The specified schema name "dbo" either does not exist or you do not have permission to use it




question 2 :
The granularity of "grant permission to useraccount" command is database,while i want to get a table level of granularity.. how?

thanks