I want to quickly point out that this could be an issue between ActiveTcl and Tcl.pm (which is where the failed dlopen(…) message comes from), rather than Tkx specifically.

(I might follow up later if I have more info, because I may have encountered this issue myself recently, but did not investigate it much before trying MagicSplat instead. Edit: My issue was something much different: bad default values in tclConfig.sh in both ActiveTcl and MagicSplat—not a 32/64-bit mismatch.)