I solved this by adding .to_json
and some heading information
@result = HTTParty.post(@urlstring_to_post.to_str,
:body => { :subject => 'This is the screen name',
:issue_type => 'Application Problem',
:status => 'Open',
:priority => 'Normal',
:description => 'This is the description for the problem'
}.to_json,
:headers => { 'Content-Type' => 'application/json' } )