WP_Query Not Working with Variable

Question

If I use this code(code not complete, this is the problem section), the posts appear properly. NOTE the "new WP_Query('cat=2,3,5,6,7,8,9');":

$catslugs = array('academic',/*'adventure',*/ 'arts', 'religious', 'special-interest', 'special-needs', 'sports','teen');//Must upate as new Main categories are added 
    $out = array();
    foreach($catslugs as $slug) {
        array_push($out, get_category_by_slug($slug)->term_id);
        $CatIDs= implode(',', $out);
        }
    //featured category ID = 153
    //academic category ID = 2
    //adventure category ID = 4
    //arts category ID = 3
    //religious category ID = 5
    //special-interest category ID = 6
    //special-needs category ID = 7
    //sports category ID = 8
    //teen category ID = 9
    $CatIDsCode="'cat=".$CatIDs."'";
    $camp_posts_bynumber = new WP_Query('cat=2,3,5,6,7,8,9');

    if( $camp_posts_bynumber->have_posts() ):

If I change it to this it doesn't. Instead it shows ALL categories including "Uncategorized". What am I doing wrong? Is it something with "have_posts()"

$catslugs = array('academic',/*'adventure',*/ 'arts', 'religious', 'special-interest', 'special-needs', 'sports','teen');//Must upate as new Main categories are added 
$out = array();
foreach($catslugs as $slug) {
    array_push($out, get_category_by_slug($slug)->term_id);
    $CatIDs= implode(',', $out);
    }
//featured category ID = 153
//academic category ID = 2
//adventure category ID = 4
//arts category ID = 3
//religious category ID = 5
//special-interest category ID = 6
//special-needs category ID = 7
//sports category ID = 8
//teen category ID = 9
$CatIDsCode="'cat=".$CatIDs."'";
$camp_posts_bynumber = new WP_Query($CatIDsCode);

if( $camp_posts_bynumber->have_posts() ):

OR

$catslugs = array('academic',/*'adventure',*/ 'arts', 'religious', 'special-interest', 'special-needs', 'sports','teen');//Must upate as new Main categories are added 
$out = array();
foreach($catslugs as $slug) {
    array_push($out, get_category_by_slug($slug)->term_id);
    $CatIDs= implode(',', $out);
    }
//featured category ID = 153
//academic category ID = 2
//adventure category ID = 4
//arts category ID = 3
//religious category ID = 5
//special-interest category ID = 6
//special-needs category ID = 7
//sports category ID = 8
//teen category ID = 9
$CatIDsCode="'cat=".$CatIDs."'";
$camp_posts_bynumber = new WP_Query($CatIDs);

if( $camp_posts_bynumber->have_posts() ):

Answer 1

I'm pretty sure it's because you've got mixed nested quotes when you're setting $CatIDsCode.

So this should fix it:

$camp_posts_bynumber = new WP_Query (array ('cat' => $CatIDs));

P.S. Move $CatIDs= implode(',', $out); outside of the foreach loop. :)