Multiple flat project build error

Hi, i’ve 3 flat project: /-- Project1
– Project2
– Project3

Project1 depends by Project2 and Project2 depends by Project3.

project1 build.gradle {
compile project('Project1)

project2 build.gradle {
compile project('Project2)

Now if i do in project3 “gradle build” works,
if i do in project2 “gradle build” worrks,
if i do in project1 “gradle build” says: "Project with path ‘Project3’ could not be found in project ‘Project2’.

Can sameone help me??