Why is my urine not reading ammonia/ammonium?

Hello. I am building an aquaponics system, and I would like to try out peeponics first to start the nitrogen cycle without fish for now.

I have read a few websites such as:

https://sites.google.com/site/aquapanaponics/4-project-updates/pee-ponicsphplanting

http://community.theaquaponicsource.com/profiles/blogs/how-to-build-a-4-x4-ebb-flow-bioponics-peeponics-system?id=4778851%3ABlogPost%3A417362&page=1#comments

http://www.aquaponiclynx.com/pee-ponics

Specially from the latter, I understand that its a matter of storing my urine for a month and then the ammonia-ammonium readings should start peaking.

I'm using an API Test Kit to detect pH and ammonia levels:

http://www.apifishcare.com/product.php?id=580#.VZyiXrzarbM

The problem is, after 7 weeks, I cannot get the ammonia-ammonium test kit to detect the slightest ammount of it!

It's always been 0!

pH did raise after I left one of the bottles without its cap and measured a wekk later, around 8.8, but thats it. Without being able to read ammonia, I would not know how much urine I have to dissolve in my 200L aquaponic system.

I have been inyecting urine directly from the bottles I stored them in, and into the testing tubes (5ml).

Any help will be welcome.

Edited July 8, 201510 yr by jpms