The badge only reads free ammonia, a lot of tests (like api) read total ammonia. Seachem says free ammonia is what is toxic, someone smarter than me would have to comment on that..How long has been in the water for? Mine was reading safe for a couple weeks, but there was absolutely ammonia in it.
The seachem ammonia test can be used with Cupramine, per their website if you what to double check the badge reading.
Water change can't hurt, just monitor your copper level