You copied and pasted your resume
For all intents and purposes, LinkedIn should be your resume on steroids. You have an opportunity to hyperlink to your work, references, and previous employers. You can highlight big projects you've worked on, and shed some light on what you've achieved. Include certifications, references, all of your education, and anything else that can make your profile more robust.
Bonus: LinkedIn has a built-in Resume Maker that can help adapt your skillfully-made profile into a streamlined resume.
You didn't check your grammar Having a few typos won't necessarily lose you a gig doing software analysis or operating a crane, but the mark of a professional is attention to detail. At the very least, a lack of errors shows you are trying. "Like a resume, this is for professional use and you want to put your best foot forward," according to Ceren.