Cannot send messages using arduino on NB-IoT SARA

Hi everyone,
I just got a Sodaq NB-IoT SARA board. I’ve successfully connected it to my network operator. Now I want to send messages using it, I tried using the sendMessage function but it cannot send a message, however, there is no problem when I enter the AT commands manually . The same happens when I try to open a socket to send UDP messages. Any ideas?
Thank you