error:bad screen distance "" at c:/Perl/site/lib/Tk/Submethods.pm line 37.

Tk::Error: bad screen distance "" at c:/Perl/site/lib/Tk/Submethods.pm line 37.
 Tk callback for winfo
 Tk::Submethods::__ANON__[c:/Perl/site/lib/Tk/Submethods.pm:37] at c:/Perl/site/lib/Tk/Submethods.pm line 37
 Tk::ProgressBar::_arrange at c:/Perl/site/lib/Tk/ProgressBar.pm line 99
 Tk::After::once at c:/Perl/site/lib/Tk/After.pm line 89
 [once,[{},after#858,idle,once,[_arrange,{}]]]
 ("after" script)
Tk::Error: Can't set -variable to `SCALAR(0x3c55a48)' for Tk::ProgressBar=HASH(0x41621e8): Bizarre copy of ARRAY in leave at c:/Perl
/site/lib/Tk/Trace.pm line 89.
 at c:/Perl/site/lib/Tk/Derived.pm line 294

 at c:/Perl/site/lib/Tk/Derived.pm line 306
 Tk callback for .frame.button
 Tk::__ANON__[c:/Perl/site/lib/Tk.pm:252] at c:/Perl/site/lib/Tk.pm line 252
 Tk::Button::butUp at c:/Perl/site/lib/Tk/Button.pm line 113
 <ButtonRelease-1>
 (command bound to event)
 error:Bizarre copy of ARRAY in leave at c:/Perl/site/lib/Tk/Trace.pm line 89.