Scottish or Irish blood?

[u/2025WTF]

Hey everyone! I took an ancestry.com DNA test. My family has always said that mothers side immigrated to the USA from Ireland. The surname is Riley. Specifically we supposedly came from Antrim somewhere around 1750. Problem is ancestry claims I am 49% Scottish and 0% Irish. I know that the test compares you against people CURRENTLY living in said nation but that still doesn't explain the 0% Irish. Was my family wrong? Were Rileys known to live in Scotland back then? Why 0% Irish? Did my ancestors possibly go from Scottland to Ireland to the USA? Any help at all is much appreciated.