How to get the value from a listbox populated by a query in access 2007?

Can the code be placed in the form with the list boxes?
Then you could refer to them without the qualifiers, like this
id_proyecto.Value
id_muestra.Value

you mean, in the main form, like “On Current”? Im sorry, im not an expert… i mean, access is a little strange for me.
I’ve put code on buttons, via the macro builder, for opening forms.
But the code for this is in the main form window…. Look, im trying a simpler approach: the button pops a message box with the listbox value. but im not getting nothing, just a blank space between my strings…. (also with the whole window code here)

Option Compare Database
Private Sub Form_Load()
Me.Move _
Left:=100, Top:=100
End Sub

Private Sub creanalisis_Click()
MsgBox “the value is ” & id_proyecto.Value & ” for the listbox”
DoCmd.Close
End Sub

You probably tried this already, but is there a selection in the list box? When it first opens, nothing is selected, and you would get blank space between strings.

Now that you say it, I’m thinking that I used the Listbox control to display the current selection; I populate it with a sql query with a value from the another open form by writing in its row source:

SELECT DISTINCT tabla_proyecto.id_proyecto FROM tabla_proyecto, tabla_muestra WHERE tabla_proyecto.id=[Forms]![selecciona_proyecto]![txt_id];

so, the Listbox control displays the result of the query; now Im thinking that maybe the result here is one option, maybe there’s more options and Im not referring programmatically right to the option; but, i tried that before by trying with “Me!id_muestra.SelectedItems(0)” and “Me!id_muestra.Value” and nothing

maybe its the control type, but i tried a textbox control and couldnt make it work with a query like the listbox…