#7 recieve error when adding fields

[Anonymous]

Couldn't add field toc_id.
MySQL said: Invalid default value for 'toc_id'

the sql that I am attempting to execute is:
'ALTER TABLE `list` ADD `toc_id` VARCHAR( 10 ) NOT
NULL ;'

This work fine from both the MySQL monitor.

[Nobody/Anonymous]

Logged In: NO

Seems to be only when adding a field with a default 'null' value.