I've installed coorectly using default path; and made sure
all dll's and exe files for regina and rexxtk are in
c:\winnt\system32 (which is in the PATH)
But still the RXFUNCADD fails :
Could not find any supported Tcl/Tk DLL.s
Both Regina and Rexxtk .EXE files can be accessed
anywhere , so the PATH works.