saying

adding a die statement makes it reture "Died at sendfile.pl line 28"...

is a little ambiguous. did you do this?

27 :        } elsif(-d "$ARGV[0]") {
28 :             die;
29 : print "Copying path to $Single_User_Directory - ";
30 :              mkpath([$ARGV[0], $Single_User_Directory], 1, 0711);
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or this

27 :        } elsif(-d "$ARGV[0]") {
28 :            print "Copying path to $Single_User_Directory - " || d
+ie;
29 :            mkpath([$ARGV[0], $Single_User_Directory], 1, 0711);
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? Although you list line 28 as the dying line that doesn't make sense with the original listing... I suppose you have

mkpath([$ARGV[0], $Single_User_Directory], 1, 0711) or die;
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try something more verbose :

mkpath([$ARGV[0], $Single_User_Directory], 1, 0711) or die "Unable to 
+mkpath!!! perl reports $! ---;
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the secret is $! -- without it, you're rendering your dies useless.