routes in ci shows white blank screen

$route[ 'courses' ] = 'courses';
    $route[ 'courses/(:any)' ] = 'university/courses/$1';
    above open  on project/courses/new
    but not open project/courses  will show white blank screen;
   
    $route[ 'courses' ] = 'courses';
    $route[ 'Courses/(:any)' ] = 'university/courses/$1';
   
    ```this code  will open both url,```
   
    why  this happened

Change, first 

PHP Code:

$route[ 'Courses/(:any)' ] = 'university/courses/$1'; 
$route[ 'courses' ] = 'courses';