Removing CDR-220 radio

[jpc763]

Hi,

I am ready to bring out the hammer!

I am trying to remove the CDR-220 radio using the special tools I purchased from discount car stereo along with the cable to hook an ipod up.

Their instructions are:
HOW TO USE
* Insert key into slots with straight edge facing away from the radio (see detailed image)
* Push in on key until it locks (clicks). Do the same in other slots. Pull radio outwards using key rings (see detailed image)
* To release keys simply depress spring tabs on either side of radio pull keys outwards.

I have inserted the keys into the two slots at the bottom of the radio, but no click and they just slip in and out.

What is the problem?

Thanks in advance, John