Make sure the V45 version is correctly named as "intuition.library", and resides in LIBS:, that is, without the "-v45" in the file name. Also, you need to make sure that you "LoadModule" this library in your startup-sequence, e.g.
LoadModule LIBS:intuition.library
in the startup-sequence will do that for you. Note well: If you are using Cybergraphics, you cannot use the V45 version of intuition.