no send with the module lora b-l072z-lrwan

[MArna.19]

hello,

I use the B-L072Z-LRWAN Module in Lora, i want test the AT Command

I Join the module AT+JOIN

AT+NJS=? ==> 0

I send AT+SEND=12:hello

the response:AT_ERROR

I don't understand why?

best regard

Michel