an IN clause with a bind variable

What is the trick to using a bind variable with an IN clause?

If I assign 3, 5, 7, 10 to :1 and parse the following statement is parses correctly but give the error ORA-01722 (invalid number) upon execution.

SELECT col1 FROM table1 where col1 IN (:1);

All the other SQL statements are working fine. It is only failing when there is an IN clause.

Thanks,

Scott

Details:
C program making OCI calls
Oracle 7.3.4
DEC Unix Received on Tue Aug 25 1998 - 16:28:02 CDT