Why does this error, ERROR: relation "[name of function/Views/Trigger Functions]" does not exist, come up in pgAdmin III?

Why does this error, ERROR: relation "[name of function/Views/Trigger
Functions]" does not exist, come up in pgAdmin III?

I'm just new to pgAdmin so I don't really know what causes these error:
ERROR: relation "ongoingprojects" does not exist
LINE 1: SELECT * FROM ongoingProjects;
^
*** Error ***
ERROR: relation "ongoingprojects" does not exist
SQL state: 42P01
Character: 15
Even if the Function/View exist in the schema. Why does it give that
error? And what shall I do to fix it? Thanks!