unresolved installation problem

[babinsm1]

hysplit, Tcl, and Tk are installed in /Users/babinsm1/
my PATH contains /opt/homebrew/Cellar/tcl-tk/9.0.3/bin
from hysplit/working I run ./hysplit.tcl (the linked file for hysplit.tcl in guicode)
Error in startup script: can't read "tcl_dir": no such variable
while executing
"file join $tcl_dir .. guicode htmlbrws.tcl "
(in namespace eval "::html" script line 2)
invoked from within
"namespace eval html {
source [file join $tcl_dir .. guicode htmlbrws.tcl ]
namespace export load_html
}"
(file "./hysplit.tcl" line 610)

If I type echo $tcl_dir from the command line, it says /Users/babinsm1/tcl9.0.3
which is correct. So why does the script report that there is no such variable? Would greatly appreciate any help. Thank you.