DNA Pairing(help)

Hey, guys, can anyone help me out on this? I am not sure what I am I doing wrong as i cannot pass the tests.

var pair_1 = ["A","T"];
var pair_1_reverse = ["T","A"];
var pair_2 = ["C","G"];
var pair_2_reverse = ["G","C"];
var result = [];
function pairElement(str) {
  str = str.split("");
  var i ;
  for(i = 0;i < str.length;i++){
     if(str[i] === "A" ){
         result.push(pair_1);
     }
     else if(str[i] === "T"){
       result.push(pair_1_reverse);
     }
     else if(str[i] === "C"){
      result.push(pair_2);
    }
     else{
      result.push(pair_2_reverse);
    }
  }
  return result;
}

pairElement("CTCTA");

Thanks in advance for your help!

Of course. Spot on! I will be on the lookout for mistakes like that.