FOUND IT!!
Code:
Private Sub Report_Open(Cancel As Integer) Dim objchart As Chart
Dim Values As String
Dim CV As Object
Set objchart = Me.StockGR
Set DB = CurrentDb
Set rs = DB.OpenRecordset("SELECT DISTINCT azienda FROM qryAssoreti_Stock")
If rs.RecordCount > 0 Then rs.MoveFirst
Do Until rs.EOF
If Values = "" Then
Values = Values & "[" & rs!Azienda & "]"
Else
Values = Values & ";[" & rs!Azienda & "]"
End If
rs.MoveNext
Loop
With objchart
.ChartTitle = "Livelli di stock per trimestre"
.RowSource = "qryAssoreti_StockXGrafico"
.ChartAxis = "data"
.ChartValues = Values '"[Azimut Consulenza Per Investimenti Sim Spa];[FIDEURAM - INTESA SANPAOLO PRIVATE BANKING SPA]"
.PrimaryValuesAxisFormat = "currency"
'.ChartLegend = "[Azimut Consulenza Per Investimenti Sim Spa]"
.HasLegend = True
'Set CV = .ChartValuesCollection
Set CV = .ChartSeriesCollection
For Each CV In .ChartSeriesCollection
CV.DisplayName = Replace(CV.DisplayName, "SumOf", "")
.HasLegend = True
Next
End With
rs.Close
Set rs = Nothing
Set DB = Nothing
End Sub