Run time error 424 .. object required - sql

Question

I am getting this error in Microsoft Access:
runtime error 424 object required
And below is the VBA code that I have used on the backend of a button:
VBA Code
Private Sub Command87_Click()
If Me.phase <> "" Then
Me.lst_caseItems.RowSource = " " & _
"SELECT tbl_master.fld_masterID, " & _
"tbl_master.fld_masterActionNo AS ActionNumber, " & _
"tbl_master.fld_masterStudyActionNo AS StudyActionNo, tbl_master.fld_masterIssuedTo," & _
"tbl_master.fld_masterRev AS Rev, tbl_phases.fld_phase AS Phase, tbl_studies.fld_study AS Study, " & _
"FROM ((tbl_master LEFT JOIN tbl_studies ON tbl_master.fld_studyID = ' " & tbl_studies.fld_studyID & " ') LEFT JOIN tbl_phases ON tbl_master.fld_phaseID = ' " & tbl_phases.fld_phaseID & " ') LEFT JOIN tbl_locations ON tbl_master.fld_locationID = ' " & tbl_locations.fld_locationID & " ';"
End If
End Sub

Answer 1

In your current code, VBA thinks tbl_studies.fld_studyID is a variable hence asking for an object.
With your current code;
' " & tbl_studies.fld_studyID & " '
The " CLOSES the SQL statement, then your ampersand tbl_studies or etc tells VBA to add in the value of the variable tbl_studies.fld_studyID then the ampersand followed by " reopens the SQL statement within VBA (so on compile all flows as necessary). As you have no variable named studyID it looks like this is the cause of your object required.
To get around this, you either need to assign a variable to the ID you want (such as dim X as long then x = studyIDyouwanthere) or write your query correctly so it links to the studies table with field studyID. Looking at it more closely it looks like you just need to write the query properly in the VBA window so it's syntactically correct (in VBA's interpretation) try the following;
Private Sub Command87_Click()
If Me.phase <> "" Then
Me.lst_caseItems.RowSource = " " & _
"SELECT tbl_master.fld_masterID, " & _
"tbl_master.fld_masterActionNo AS ActionNumber, " & _
"tbl_master.fld_masterStudyActionNo AS StudyActionNo, tbl_master.fld_masterIssuedTo," & _
"tbl_master.fld_masterRev AS Rev, tbl_phases.fld_phase AS Phase, tbl_studies.fld_study AS Study, " & _
"FROM ((tbl_master LEFT JOIN tbl_studies ON tbl_master.fld_studyID = tbl_studies.fld_studyID) LEFT JOIN tbl_phases ON tbl_master.fld_phaseID = tbl_phases.fld_phaseID ) LEFT JOIN tbl_locations ON tbl_master.fld_locationID = tbl_locations.fld_locationID;"
End If
End Sub
When you are joining on queries in VBA you don't join based on the values of variables, you'll only be using them for your select part or having/where/group BY not on the joins.