Properly calculate the effective scale, so POI integration works when the world map is scaled down

diff --git a/TomTom_POIIntegration.lua b/TomTom_POIIntegration.lua
index 529b0af..e6a5d71 100644
--- a/TomTom_POIIntegration.lua
+++ b/TomTom_POIIntegration.lua
@@ -3,7 +3,7 @@ local function POIAnchorToCoord(poiframe)
     local frame = WorldMapDetailFrame
     local width = frame:GetWidth()
     local height = frame:GetHeight()
-    local scale = frame:GetEffectiveScale()
+    local scale = frame:GetScale()
     local cx = (x / scale) / width
     local cy = (-y / scale) / height