I'm using Ruby for my tests, but if you have the correct element and you are using the press action, you need to release the press. Also you usually need to pass in the elements x/y coordinates.
In Ruby it would be something like
element = driver.find_element(locator)
x_position = element.location_rel.x
y_position = element.location_rel.y
Appium::TouchAction.new.press(x: x_position, y: y_position).release.perform
For Java checkout this link:
http://appium.github.io/java-client/io/appium/java_client/TouchAction.html#press(int, int)