Why isn't my if-statement not triggering?

The object of this is to first print buttons based on groups fetched from database table for groups. After selecting a group, it should allow you to select a driver from that group in the dropout menu. I've tested the $kops for fecthing driver result, it works. The button selecting the group ID works too. But somehow, I cannot compare the group ID from the button to the group ID from the driver database table. If I remove the if statement, it show all the drivers, regardless of group they are assigned in.

function getTab(clicked_id) {
var x = clicked_id;
document.getElementById("work").innerHTML = x;

Above is the script that fetches an group ID from a button. The buttons are generated upon group ID's, and their amount is based on how many are in the database. Reason why there are no static, hardcoded buttons.

$tab_in = '<p id="work"></p>' ;

A variable to store the group ID from the button

   while($kops = mysqli_fetch_assoc($driver_rslt)){
     if ($tab_in === $kops['opsryhma']){
   echo'<option value="';echo $kops['ops_id']; echo'">'; echo $kops['opsnimi']; echo'</option>';

And in here, the previously mentioned group ID is compared to a another group ID fetched from another table in the database. THE PROBLEM: that first group ID does not appear to be working here. I can echo $tab_in it above the option and it will print out the right ID, but it will not appear inside the if statement for the comparison.

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