failing to run gnucash 2.4 on MacOSX Leopard (10.5.8)

[Johann George]

I've just downloaded the latest gnucash 2.4 for MacOSX and am attempting to
run it on Leopard (10.5.8) and get the following error:

Dyld Error Message:
 Library not loaded: /usr/lib/libltdl.3.dylib
 Referenced from:
/Volumes/Gnucash-Intel-2.4.0/Gnucash.app/Contents/MacOS/Gnucash-bin
 Reason: image not found

I also tried it on Snow Leopard (10.6.5) and it seems to run without
complaint.

We have been previously running gnucash 2.2.9 on Leopard for the last year
and it seemed to run fine but upgrading to gnucash 2.4 gives this error.

Has anyone had the same experience?  Incidentally, I'm really a Linux user
and am not that familiar with Macs.  Perhaps I am just missing a library?
 If so, how would I install it?

Thanks.

Johann