[CentOS] fonts on centos 4 and 5

I am running centos 4.x and  5 x86_64 and using the script below and the 
slider bar at the bottom
I cannot get fonts bigger than 50.

someone  else posted a followup and said he has the same issue.
What can be happening here??? xlsfonts shows that bigger fonts are 
available.

How can I get bigger fonts???

Note - I had to do a "yum install tk" also...

Thanks,

Jerry
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#!/usr/bin/wish

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