P: Save for Web, unable to use short cuts in save dialog (Copy/Cut/Paste) file name

When I am saving a file for web, I adjust the size of the image or file and when the dialog box opens for me to put in my file name, I hit command+v to paste in the name I want to use to save the file. However it doesn't paste in the save as dialog box, it pastes in the height dimension box. I have made sure my cursor is in fact in the 'save as' dialog box however no matter what I try, I can't paste in the box unless I right click in the dialog box and click 'paste'.