I am running into a weird issue that my custom SharePoint webpart cannot retrieve the AF Attribure value if that Attribute refers to a PI Point, but get the "Tag Name is not specified in ' --- Attr Path --- ' error instead. (Using AFAttribute.GetValue() to retrieve the value.)
Found this issue in my new TEST environment, but not in the new Development environment, where both contents were upgraded from SP2010 to SP2013. By looking into the debugger, the attribute object simply doesn't have anything in the "ConfigString" property, even though the DataReference.Name is recognized as "PI Point" in code, and PI Point config string is set correctly in the PI System Explorer. I also noticed the AFAttribute.DataReference.ConfigStringStored property has the PI Point string, but just not the AFAttribute.ConfigString.
Any idea? Thank you.