SenseCap T1000 beginner's problem


I got my T1000 tracker last week and could start it up using the ANDROID app. I wanted to test the examples from the seedstudio wiki, but failed. I followed this:

Connect to The Things Network | Seeed Studio Wiki and
TTN Mapper Configuration | Seeed Studio Wiki

I wanted to see data of my t1000 in the TTN MAPPER, but there is none. I am running a proper configured DRAGINO gateway and my sensor nodes are transferred by the gateway to TTN and via the integration into some channel at THINGSPEAK.
I can see the the data packets in the live data in the gateway console of TTN and followed the steps described with the decoder, integrations etc. but no data is appearing in TTN mapper, just my gateway …

I am sure I did something simply stupid, but I am quite sure I followed the wiki correctly …

Any idea, what I should check again?