Results page does not work correct

Hi there,

DW 8.0.2 with PHP & mySQL

Database: 9 Fields with, amongst others, the following:

Field Type Collation Attributes Null Default Extra
pack_id bigint(10) - -- No -- auto_increment
three_phase decimal(5,1) - -- Yes 0.0 ---

I have a form with "get" to search through this table and goes to
results.php
This is the SQL statement for the RecordSet:

SELECT *
FROM tractorpacks
WHERE three_phase LIKE %colname%

Name: colname
Type: Numeric
Default Value: -1
Run-time Value: $_GET['three_phase']

The default value I have changed to % without any success.

Here's my problem:
When clicking the "TEST" button and I leave the little box where I have
to put in some value OPEN, all my records display.

When I do this through my browser, no data is returned. BUT, when I put
in "1", all the records with "1" in the specific field, return.

What I want to have, is that when I fill nothing in as a criteria, all
the records must return. I have it like this at
www.sincro.co.za/alternators/index.php and this is another query from
the same db but I cannot get this one to work.

I will REALLY appreciate your help here.

Regards,
Deon