Homebrew PCBs

Hi all,

I've just had my first try at making a PCB and it failed :-(. Could you 
guys (and girls) please look to my procedure and correct me if I did 
something stupid.

I am using the kit from Conrad ( 
http://www.conrad.fr/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&storeId=10001&productId=209546&langId=-2&parent_category_rn=18950 
), which consists of a black box containing 4 UV tubes and a heated etch 
stand.

I've designed a test board using eagle and exported it as an image ( see 
www.lieron.be/pcb/small_2400dpi.bmp ).
I've printed the pattern on a transparent slide using a inkjet printer 
(Canon Pixma 5400R), with all settings to "darkest" and highest quality. 
It came out very well..
Then I put the transparent on the glass plate in the UV box and placed a 
piece of photo sensitive PCB on top of it. After 2.5 minutes of lighting 
I developed the PCB in a NaOH solution (1 liter for 35grams NaOH).
You could quickly see the process failed then, the pattern didn't show 
up, only the big black spot and the widest track were somewhat visible.
I've tried several other light times, from 1.5 minutes to 3 minutes but 
they all seem to give the same result, the small tracks are gone every time.

I've also tried putting a second identical transparent on top of the 
first one to make it darker but that didn't help either. The weird thing 
is I taped the second one using regular green DIY tape and that seemed 
to stop the UV light better then the much darker transparrent. Could it 
be an issue of the inkt not stopping UV light?

Anyways, I'm just slightly depressed now, so I need some icecream ;-)

Thanks in advance for suggestions and greetings,


Ronald