QT Creator Unable to find STL outside of project, Bad install?

[egildon]

Hello,
I am new to C++ programming.
I was trying to write a simple hello world program.
I created a New File/C++ Source File...
Then I attempted to use includes from the STL

// Game1
//
// Demonstrates constants
 
#include <iostream>
using namespace std;
...

// Game1
//
// Demonstrates constants

#include <iostream>
using namespace std;
...

To copy to clipboard, switch view to plain text mode 

The: "include <iostream>" is always listed (highlighted) as an error. Why is this only happening here but not when I create a project?
Is there something wrong with my install?

Thanks in advance,