RTL-SDR tuners usually have very good reception between 50 and 1000 MHz, which includes the FM broadcast band. It is easy to overload the analog-to-digital converter, so it's important to make sure the gain is not set too high. Setting the gain too low could also prevent reception if you're far from the transmitter. If you're receiving from indoors, interference from electronics in your house can cause trouble, and walls attenuate radio signals. You could try moving the antenna, or check whether it works better outdoors.