How do you update workitems using Perl LWP UserAgent?

I've been trying to post a new workitem to my RTC server then try to use a PUT to update the state of the workitem. So far, I only get a 406 not acceptable error. Here's a section of the code I'm running:

my $url = 'https://serveraddress:9443/ccm/resource/itemName/com.ibm.team.workitem.WorkItem/' . $workItemID;

my @hdrs = (
            'Accept' => 'application/xml',
            'OSLC-Core-Version' => '2.0',
            'Content_Type' => 'application/xml');

my $response = $userAgent->get($url, @hdrs);

my $str = $response->as_string;
my $find = "request.workflow.state.oldState";
my $replace = "request.workflow.state.newState";
$find = quotemeta $find;

$str =~ s/$find/$replace/g;

my @etag = split("ETag:", $str);
@etag = split("\"", $etag[1]);
my $etag_value = $etag[1];

my @strArray = split("encoding=", $str);
$str = "<?xml version=\"1.0\" encoding=" . $strArray[1];
@hdrs = (
            'Accept' => '/',
            'Content_Type' => 'application/rdf+xml',
            'if-match' => $etag_value,
            'Content' => $str);
my $url = new URI::URL('https://serveraddress:9443/ccm/resource/itemName/com.ibm.team.workitem.WorkItem/' . $workItemID);
my $request = HTTP::Request->new("PUT", $url);
my $response = $userAgent->request($request, @hdrs);