Geographic (datum) transformation between two geographic coordinate systems doesn't work in ArcMap

Description

This problem is addressed in ArcGIS 8.1 Service Pack 1. See the Related Information section to download this pack.

Sometimes a geographic transformation doesn't work correctly in ArcMap. The layer and data frame coordinate systems are geographic coordinates.

Cause

When the layer and data frame coordinate systems are geographic, you have to zoom in to see the change in values. The display isn't refreshing properly. The current display extent is checked against the new extent. Because the two extents are the same nothing happens.

Workaround

• Do not zoom in until the geographic transformation is properly applied.
• Set the data frame coordinate system before you add any data.
• Set the data frame to a projected coordinate system that uses the geographic coordinate system you want to use. Set and apply the geographic transformation. Now change the data frame to the geographic coordinate system that you want to use.