Get value from non related table

Hi everybody,

I have a new problem with DAX

I have three table :

affect (idAffect, idProject, idTask, ...)

Project(idProject, ...)

Task(idProject, neededValue)

I have two relations beetween tables:

affect(idProject) <=> project(idProject)

task(idProject) <=> project(idProject)

Now, I want to get a value "neededValue" from task to affect.

But I can't enable an active relation without create ambiguity.

How I can get value "neededValue" in affect ?

best regard