Finding the right supplier involves both skill and luck. Make sure to do a quick Google search about the company. Look for red flags by adding the words scam, warning, or beware in the search bar.
Aside from this, suppliers on Alibaba can be very picky with what buyers they choose to work with.
You will see on the search results page the Supplier Response Rate. You will almost always see that this Response Rate is far lower than 100%. Alibaba suppliers will often simply ignore many buyer requests.