How to re-name a column?

I am using Query Browser version 1.1.2, MySQL Administrator 1.0.14, MySQL
Version 4.1.7-nt on Windows XP Service Pack 2

ALTER TABLE `purpleflavours`.`purchaseorderitem` CHANGE COLUMN
`PurchaseCost` `PurchaseOrderItemCost` DOUBLE UNSIGNED ZEROFILL CHARACTER
SET NULL COLLATE NULL NOT NULL DEFAULT 0000000000000000000000

Generates when I click the apply changes button in the MySQL Table editor
window after changing the column name.
This generates an error telling me I have an error in my SQL Syntax

Can anyone tell me what is wrong?

By the way I can use the table editor to change VarChar column names with no
problem but I always get a syntax error if the column type is not a VarChar,
i.e. Double, DateTime, MediumBlob, Integer etc...

Many thanks in advance

Regards

James West