SQLite DB Browser: invalid operand for regexp

I used DB Browser for SQLite version 3.6.0; SQLite Version 3.8.9. This application already supports Regular Expression out of box (sqlitebrowser). I can use regexp on column brand but failed on column revision;

For example

SELECT brand,revision FROM TDevice where TDevice.brand regexp '^ASUS$'

and the result is 114 Rows returned from: SELECT brand,revision FROM TDevice WHERE TDevice.brand regexp '^ASUS$'; (took 51ms)

However, if regexp is applied on different column, then I get the error

SELECT brand,revision FROM TDevice WHERE TDevice.revision regexp '^ASUS$';

and the error message is invalid operand: SELECT brand,revision FROM TDevice WHERE TDevice.revision regexp '^ASUS$';

Both brand and revision are of TEXT type. The table creation schema is as below:

CREATE TABLE `TDevice` (
`id`    INTEGER NOT NULL,
`brand` varchar(128) NOT NULL,
`model` varchar(128) NOT NULL,
`revision`  TEXT,
PRIMARY KEY(id)
);