Are you sure you have it plugged into a phantom power source? This is a powered mic - it needs power to work correctly. Phantom power means power sent to the mic over the signal lines, which requires a positive, negative, and ground. That's why the XLR connector has 3 poles on it.
The 3.5mm plug in the included adapter also has 3 poles, whereas the standard mic port only has 2 poles (signal and ground). So while it will fit into the computer's 3.5mm mic socket, that doesn't mean it'll work properly connected like that. You need to an XLR adapter which supplies phantom power, or a balanced 3.5mm mic input which supplies phantom power.