Embedded Tcl/Tk compiled under 10.5 runs on 10.5 but not on 10.4

The program runs fine on 10.5 but not under 10.4.

This is the error on 10.4:

Can't find a usable init.tcl in the following directories:
     /Library/Frameworks/Tcl.framework/Versions/8.5/Resources/Scripts
./lib/tcl8.5 ./lib/tcl8.5 ./library ./library ./tcl8.5.7/library
./tcl8.5.7/library

The framework paths are set into the binary with 'install_name_tool' and 
'otool -l' shows the correct paths under both 10.4 and 10.5.

The same program under 10.5 runs fine - it's as if under 10.4, the 
tcl/tk-framework paths in the binary are being ignored - but they are there.

Any ideas why this is happening?

Andy

[ full program: inivis.com/ac3d/download/release6/ac3dmac6528.tgz  ~8 meg]
[using tcl/tk8.5.7 embedded build on system 10.5.]

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