I'm trying to import pycassa library in a Python project in Aptana 3, but in the line "import pycassa" it show me the next error: "Unresolved import: pycassa". I installed pycassa with easy install and if I run "import pycassa" in a python shell it run with no errors. If I run the Aptana project run with no errors too, but the error mark continues. Why?

Sorry for my english.