Message type to print in MIRO

Hello guys,

my problem is this:

I must parametrize the output message in MIRO to print the invoice but when I run MIRO and I select from menu the voice 'Go to' > 'Message' >'Header and I insert the output type(message,for example MLPP) the system gives me message n°V0104..?What is it means'because my problem is to set my output type as a default like for example in Purchase Order in which I can insert several output type(message) as a default.For example NEU or others...

I have already parametrized the message determination for Logistic invoice but I can't associate these message type of print as a default in my Logistic Invoices-->must I execute this association in SPRO or in other ways?

Thanks in advance,I promise 10 points for a fast resolutive answer.

Bye

Maximilian