Good point. With Tk already installed, Tk::SplitFrame installed for me with no problems:

13:58 >p5u v Tk Tk::SplitFrame
Tk
        C:\Perl\Strawberry\strawberry-perl-5.20.0.1-64bit-PDL\perl\sit
+e\lib\Tk.pm: 804.032

Tk::SplitFrame
        Not found

14:20 >cpanm Tk::SplitFrame
--> Working on Tk::SplitFrame
Fetching http://www.cpan.org/authors/id/D/DK/DKWILSON/Tk-DKW-0.02.tar.
+gz ... OK
Configuring Tk-DKW-0.02 ... OK
==> Found dependencies: Tk::TiedListbox
--> Working on Tk::TiedListbox
Fetching http://www.cpan.org/authors/id/A/AC/ACH/Tk-Contrib-0.07.tar.g
+z ... OK
Configuring Tk-Contrib-0.07 ... OK
Building and testing Tk-Contrib-0.07 ... OK
Successfully installed Tk-Contrib-0.07
Building and testing Tk-DKW-0.02 ... OK
Successfully installed Tk-DKW-0.02
2 distributions installed

14:21 >p5u v Tk Tk::SplitFrame
Tk
        C:\Perl\Strawberry\strawberry-perl-5.20.0.1-64bit-PDL\perl\sit
+e\lib\Tk.pm: 804.032

Tk::SplitFrame
        C:\Perl\Strawberry\strawberry-perl-5.20.0.1-64bit-PDL\perl\sit
+e\lib\Tk\SplitFrame.pm: 1.01

14:22 >
[download]

I’m also using Strawberry Perl portable (on Windows 8.1, 64-bit):

14:27 >perl -v

This is perl 5, version 20, subversion 0 (v5.20.0) built for MSWin32-x
+64-multi-thread
[download]

Hope that helps,