why is my array_sum showing the wrong number?

I have this array and I want to add the values:

$sustainCapital_arr = Array ( [0] => 2,759 [1] => 3,269 [2] => 3,481 [3] => 3,573 [4] => 3,997 [5] => 4,421 [6] => 10,999 )

now, interestingly array_sum is giving me an incorrect number:

$total_Sustaining = array_sum($sustainCapital_arr);     output: 28 ???

Output should be 32,499.

Now, I also tried to use a foreach loop and the same happens. What the hell is going on here?

$total_Sustaining = 0;
foreach ($sustainCapital_arr as $key=>$value){
                            
   $total_Sustaining += $value;
}

output is again 28!!!

What am I doing wrong here?

>Solution :

$total_Sustaining = 0;
foreach ($sustainCapital_arr as $key=>$value){
                            
   $total_Sustaining += filter_var($value, FILTER_SANITIZE_NUMBER_INT);
}