Show blank until something but the values to show when selected is in another table

[electrobrit]

I have one table with Project Notes (ProjectTable2[Notes]) and one table with Project Names (ProjectTable1[ProjectName])
(they are related through ProjectID in both tables)
I have a table of the projects and a seperate table visual with the notes but would like to show notes empty (or text) until a project is selected then show the notes.

I can't get this to work being they are seperate tables. It does not give me an option to select another table, only another measure.

Show notes = If(IsFiltered(ProjectTable1 ([ProjectName]), ProjectTable2[Notes])
Tried this too, won't let me select the notes column from another table:

Show text = if(Isfiltered(ProjectTable1 ([ProjectName]), ProjectTable2[Notes], "Select a project to view notes")

Can someone help me with what I am doing wrong with this?
I know I could merge but seeing if I can do without a merge first.
Can you do measures to say until something in this table is fitlered, show blank, then when it's filtered, a field from another table show show (again, they are related)?
thank you in advance!

[jdbuchanan71 · Accepted solution]

Hello @electrobrit 

Give this a try.  I will show "Select a project" if none or more that one project is selected.  If a single project name or id from the ProjectTable1 is selected it will show the note.

Note = 
VAR _Project = SELECTEDVALUE ( ProjectTable1[ProjectID] )
RETURN 
IF ( 
    ISBLANK ( _Project ), 
    "Select a project",
    CALCULATE ( 
        MAX ( ProjectTable2[Notes] ),
        ProjectTable2[ProjectID] = _Project
    )
)

None selectedProject Selected

I have attached my sample file if you need it.

[electrobrit]

@jdbuchanan71 worked perfectly, many thanks!