Fill standard System Matrix - Operation is not supported on System Forms

Hi all,

I have created a UI Matrix that successfully transfers values to an array.

However I try to fill a sales order (itemCode, quantity) with the values of the Array.

I use DataSources for this action, but I get the message " Operation is not supported on System Forms".

Is there any action to procceed in order to fill Sales Order lines efficiently?

Thanks in advance,
Vasilis