Still no ammonia or nitrite reading?

[Sidman24]

I started to cycle a 30 gallon tank a week or so ago with 7 lemon tetras and 4 cories. So far I have lost 2 lemon tetras but everyone else seems to be doing fine. They are active and eating. However I'm still getting no reading of ammonia or nitrites.. Will this take awhile? Should I do something different? I try not to feed so much as I know this can affect the process. I even tried to squeeze a little media from an existing filter to the new tank. Didn't seem to do much.