How to fix an if, elseif, and else statement causing an HTTP 500 error?

I have an if, elseif statement causing an HTTP 500 Error. I would really appreciate the help figuring such a simple problem out. Thank You!

I have tried changing my conditions, deleting the elseif (which worked), alternating between elseif and else if. I have searched Google, and the answer is nowhere to be found.

<?php if($row7Count == 0) {
// This code works fine
}
elseif($editAgent != null) {
// This code causes HTTP 500 error
}
else {
//This code works fine
}

Expected results is to execute any code within elseif statement, even a simple echo 'testing'; does not work.

Actual results = HTTP 500 Error