<p>Yes, lack of publications. Many applicants to top graduate programs have at least a couple of publications. You get included as a non-prime author if your contribution to the project was significant. If you didn’t get included, it means that you were working without significantly contributing. </p>
<p>You are spending time on what you think is “research.” But you are not doing research, you are working as a lab tech. Working as a lab tech is fine, as it provides hands-on experience, but it should not be done at the expense of academics. Academic excellence is crucial for becoming a good research scientist. You can always get hands-on experience later, but you cannot get “good grades” later, you get only one shot at doing that.</p>