“404 not found” may be due to appending issue?

For my online survey (I am using MTurk to recruit participants) a large propotion of partcipants have reported a “404 Not Found” when clicking on the link for the experiment. One of the partcipants let me know that he got this error and was able to fix it by removing the portion of the URL the MTurk ID is happened. I am not sure why it works some partcipants but not for others, so I am potentially suspecting that I am not appending correctly this information. Here is the line of code I am using in MTurk to do this:
assignment_id_field.innerHTML = '<a target="_blank" href="https://run.pavlovia.org/CML-lab/my_online_survey&workerId=' + mturkworkerID + '"><h3><span style="font-family: Verdana;">Click here to accept and begin the survey</span></h3></a>';

Am I doing something wrong?

I figure out what was wrong. Before workerId the “&” in the URL is wrong and has to be changed with a “?”. Not sure why it was working for participants but not others.