找不到与列列表匹配的FULLTEXT索引 - 仅适用于localhost

I'm having some problem searching full text in MySQL. The code below only works on my localhost, but on my hosted server it throws an error:

"Can't find FULLTEXT index matching the column list"

I've had various attempts, also tried to alter my table but the error still remains. Note that the code is working well on my localhost, and printing out actual results, however it fails on running it on live server.

This is my code:

function relatedArticle($item, $category){
  global $con;
  $keywords = trim(removePrepositions($item));
  $keywords = str_replace(',','', $keywords);
  $keywords = preg_replace('/\s+/',' ',$keywords);
  $keyword_tokens = explode(' ', $keywords);
  $query_result = implode('+', $keyword_tokens);
  $construct = '';
  $construct = $query_result;
  $query = "SELECT DISTINCT * FROM apps WHERE Match(title) AGAINST ('$construct' IN NATURAL LANGUAGE MODE) and active = 'active' and Type = '$category' limit 4";
  $query_result = $con->query($query) or trigger_error($con->error."[$query]");
  echo "<div id='Big_container_rel'>";
  echo "<div id='container_rel'>";
  while($row = $query_result->fetch_array()) {
    echo "<div id='container1_rel'>";
    $AdTitle = pre_replace($row['title']);
    $type = strtolower(pre_replace($row['Type']));
    echo "<a href='/".$type."/".$row['appId']."/".$AdTitle."/'><img id='imgMobi' alt=".$row['title']." src='uploads/".$row['image']."'/></a>";
    echo "<br/><h4><a href='/".$type."/".$row['appId']."/".$AdTitle."/'>".$row['title']."</a></h4>";
    echo "</div>";
  }
  echo "</div>";
  echo "</div>";
}

My $construct is returning text joined with '+' sign. For example , find+fulltext+on+stack Please help avoid this problem; I tried several solutions from StackOverflow, but they haven't worked for me so please don't mark it as duplicate.