Since it's on your Module Manager page, make sure that it's enabled and that it's set to the appropriate access level (i.e. Public if you want it to be showed for everyone, Registered for registered users, etc.) Edit those settings as necessary.
Then check the module's position setting -- that will correspond to a position as defined in your template with the code (where in this example "xyz" is the name of your position):
<jdoc:include type="modules" name="xyz" />
See also this page and this one for guides.