Instead of
eval { $display };
use
eval $display;

The former executes the code $display (not the code stored in $display), which simply returns the value of $display. The latter compiles and executes the Perl code stored in $display. Both trap exceptions.

Reference: eval

Update: Roy Johnson brought it to my attention that you have insufficient slashes in your Debug argument.
&Debug("system(\"copy c:\\oldversion.txt c:\\version.txt \");", 1);
results in the string
system("copy c:\oldversion.txt c:\version.txt ");
but that's not what you want. You want
system("copy c:\\oldversion.txt c:\\version.txt");
so you should be using
&Debug("system(\"copy c:\\\\oldversion.txt c:\\\\version.txt\");", 1);