Calculated absolute path to tslib directory does not exist.

Something in the main file, folder and link structure is wrong and must be fixed! A typical document root contains a couple of symbolic links:
* A symlink "typo3_src" pointing to the TYPO3 CMS core.
* A symlink "typo3" - the backend entry point - pointing to "typo3_src/typo3"
* A symlink "index.php" - the frontend entry point - points to "typo3_src/index.php"