[CentOS] font test does not go higher than 49 - centos 4 x86_64

Below is a small script - ran by "wish -f file.tcl"

When I run this script and move the slider bar at the bottom on centos 4 
x86_64 I get increasing font sizes
from 5 to 49. Anything 50 and after is all the same size.

How do I get bigger fonts?

THanks,

Jerry

--------------------------------------
proc updateText {args} {
    set text [.c1 find withtag text]
    foreach {name size type} [.c1 itemcget $text -font] {break}
    set font [list $name $::value $type]
    .c1 itemconfigure $text -font $font
}

set c [canvas .c1 -width 800 -height 600 -bg white]
set s [scale .s1 -from 5 -to 200 -orient horizontal -var ::value -length 
400]
set text [$c create text 400 300 -text "Test" -anchor c -fill red -tag 
text -font Helvetica]
trace variable ::value w updateText
pack $c $s
------------------