Hi @thanhaim in the past I’ve had to make sure I selected the new field and published a second time. Hope this works:

The custom field would be on a Cache Extension not the base DAC. If you used the customization editor to create the field you will likely want to move the Code object it created(likely a POOrderExt Cache Extension) to your extension library(since your screenshot appears to be from visual studio) and then access the field through that Cache Extension class(POOrderExt.UsrETA).

Why do you have “.” In your field name in your screenshots?

also DAC Extensions are accessed like below for example for OOOrder View

YourDACExt docExt = Base.Document.Current.GetExt<YourDACExt>();

I suggest you take the T series course before doing Code Based Customizations.

Thank all very much. Have a good day.