Help with installing (Structures_Graph)

Dear Webmaster

I have tried installing pear and I get an error on pear/ 
Structures_Graph Download failed (please see install info below).

Is there an error on my server? how can I fix this problem as I need  
this to work before I can install "Mail' & "Mail_mime".

Thanks
Andy

Starting installation ...
Loading zlib: ok

Bootstrapping Installer...................
Bootstrapping PEAR.php............(remote) ok
Bootstrapping Archive/Tar.php............(remote) ok
Bootstrapping Console/Getopt.php............(remote) ok

Extracting installer..................
Downloading package: PEAR.............ok
Downloading package: Structures_Graph....ok

Preparing installer..................
Updating channel "doc.php.net"
Update of Channel "doc.php.net" succeeded
Updating channel "pear.php.net"
Channel "pear.php.net" is up to date
Updating channel "pecl.php.net"
Channel "pecl.php.net" is up to date

Installing selected packages..................
Downloading and installing package: PEAR.............ok
Installing bootstrap package: Structures_Graph.......downloading  
Structures_Graph-1.0.2.tgz ...
Starting to download Structures_Graph-1.0.2.tgz (30,947 bytes)
....done: 30,947 bytes
XML Error: 'not well-formed (invalid token)' on line '10'
Download of "pear/Structures_Graph" succeeded, but it is not a valid  
package archive
Error: cannot download "pear/Structures_Graph"
Download failed
Downloading and installing package: Archive_Tar-stable.......ok
Downloading and installing package: Console_Getopt-stable.......ok
Downloading and installing package: PEAR_Frontend_Web-beta.......ok
Downloading and installing package: PEAR_Frontend_Gtk2.......ok

Writing WebFrontend file ... ok
Installation Completed !


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