Changeing Sequence

All,

I have a table "mytable_id_seq" that looks like so.
   sequence_name     | last_value | increment_by |      max_value      |
min_value | cache_value | log_cnt | is_cycled | is_called
----------------------+------------+--------------+---------------------+---
--------+-------------+---------+-----------+-----------mytqble_id_seq |          4 |            1 |
9223372036854775807|
 
1 |           1 |      30 | f         | t


I have data that must be entered into the table "mytable" with pre-defined
ids (i.e. 1,3,5,7,25). Is it possible to change the sequence to start at
"26" the last value of the previous data?

Please tell me YES! I get an error: "ERROR:  You can't change sequence
relation t_staff_staff_id_seq"

Any Help would be great!

Thanks,
-pete