I just bought ammonia test strips for a relatively new 10 gallon tank after fish were swimming on bottom. These are API strips and I find the test hard to read. The pad starts yellow (good) and after dipping five seconds, waiting 1 minute, the edges are slightly green. All green bad but partial? Hate to waste more money and get another kit.
Test strips for ammonia are fairly new. They should always be sealed in their container so they do not get contaminated. Very often, ambient lighting and background issues affect the way we perceive colors. You may want to take a water sample to the aquarium shop so your test results can be verified.
If the aquarium does have ammonia, the nitrogen cycle is not working. Please open this link for more details:
Toxic nitrogen compounds can be diluted by 20 or 25 percent water changes every two or three days. After ammonia and nitrite are zero, weekly partial water changes will help maintain the biological balance.