Hi @Harry,
For overriding PrintInvoice Action on SOInvoiceEntry, You can use below code snippet.
public class SOInvoiceEntry_Extension : PXGraphExtension<PX.Objects.SO.SOInvoiceEntry>
{
#region Event Handlers
public delegate IEnumerable PrintInvoiceDelegate(PXAdapter adapter, String reportID);
[PXOverride]
public IEnumerable PrintInvoice(PXAdapter adapter, String reportID, PrintInvoiceDelegate baseMethod)
{
return baseMethod(adapter,reportID);
}
Hope, it helps!