OPC with power manager, tags in null

I have a gateway with an OPC conection to a power manager software.
The conection status is ‘conected’ but in the designer shows all the tags in null with an unknown quality.
Any hint ?

Thanks

if you want someone to help you should provide some more information…

like is this opc-ua or opc da? have you tried with an outside client like matrikon explorer or the kepware client?