Portfolio Size and Order
1. Make sure you're using the Fullwidth masonry style as Igor pointed out.
2. Make sure your images meet the size requirements as stated in the Masonry Sizing section of the User guide : http://themenectar.com/docs/salient.pdf
3 And last - if you want to order your items without changing the date, use this plugin: http://wordpress.org/plugins/intuitive-custom-post-order/