Please tell us exactly what you've done, rather than that it was correctly done, since
something isn't correct.
Which ArcGIS 10.1 service pack are you using? [At this point, it should be sp1]
Which PostgreSQL release are you using, on what platform? [I'm using 9.1.9 without
difficulty] From where did you obtain the executable?
Did you place the correct required library in the appropriate directory? [Newer libraries
are only available in Desktop and Server installs, in the 9.1 subdirectory, and it's a different
location depending on how the binary was built.]
- V