Does anyone know how to modify a column's datatype in sybaseIQ?

ie i have table: "MY\_TABLE" with col STATUS varchar(100)
i want to change it to varchar(10)

```
alter table "MY_TABLE" 
    modify "STATUS" varchar(10)

```

I have tried, the above, but it doesn't seem to be working.......

```
    Error: SQL Anywhere Error -1013024: ALTER TABLE MODIFY <column> <datatype> is not supported.
-- (db_alter.cxx 438) SQLState:  QCA24 ErrorCode: 21 

```

thoughts?