G'day marbu,

Welcome to the Monastery.

The code you posted was not the code that generated that error message. Please don't do that.

Most (if not all) of Tk's option/value pairs have a '-' before the option (e.g. -option => $value).

Your problem, in your real code, stems from writing pady, instead of -pady, in pack() (see Tk::pack).

Here's a working example:

$ perl -e 'use Tk; MainWindow->new()->Button(-text => "?")->pack(-pady
+ => 2); MainLoop'
[download]

Here's your error replicated:

$ perl -e 'use Tk; MainWindow->new()->Button(-text => "?")->pack(pady 
+=> 2); MainLoop'
bad option "pady": must be -after, -anchor, -before, -expand, -fill, -
+in, -ipadx, -ipady, -padx, -pady, or -side at /long/path/to/Tk/Widget
+.pm line 1217.
 at -e line 1.
[download]

Here's another example (with '-' omitted from the -text option in Button()):

$ perl -e 'use Tk; MainWindow->new()->Button(text => "?")->pack(-pady 
+=> 2); MainLoop'
unknown option "text" at /long/path/to/Tk/Widget.pm line 205.
 at -e line 1.
[download]

See also Tk::options.

By the way, you can completely ignore the first answer you got which talked about "unixisms" and suggested threads would fix the problem. This looks like trollage to me: I downvoted it.

Update: Linkified the "the first answer you got" text. It now points to the actual node referenced.