I have edited numerous pictures in Lightroom only to send them to a print lab(ie: mpix) and have issue with low resolution above 4x6. I can edit in Picasa and print with no resolution problem any size. What could be the problem? I like that Picasa is free but I love the resets of light room. Please help as I have many pictures to edit and get to customers as well as shoots coming up.
You probably have some wrong export settings.
Please post a screen-shoot of your export settings.
In addition, please let us know the exact version of Lightroom as well as your OS.