Downlink not sending Class a device

Hi There.

Im new chirpstack and got to a point where i have no idea what to try.

I get data from node, and the data looks good when i decode it.

But when i try to send a downlink from the web UI it just hangs there,
even when there are uplink the downlin is not sent.

Is there anything that i am missing? do i need to have a javascript decoder for it to work?

Does this mean that the message is sent to the gateway?
Is there any ways to see the trafic on the gateway itself?

this is what i see in mqtt subscribing to: gateway/gatewayid/#

qos : 0, retain : false, cmd : publish, dup : false, topic : gateway/gatewayidhere/command/down, messageId : , length : 137