Low levels of dopamine can cause depression. However depression is a multifaceted disorder with many neurotransmitters(NT) implicated in it. Serotonin is one of the most commonly depleted NT along with dopamine and norepinephrine. This is just one factor for endogenous depression, external causes also play important role like interpersonal stressors, job satisfaction, financial condition, friends etc.
Next Steps
If you feel you have symptoms of depression consult a psychiatrist.