OK.. let's give this a shot.
First of all, you're not really selecting a "range".
You're selecting a "cell", specifically the cell at row 30 column 10.
Try this:
Range(cells(30,10)).select
or even:
Worksheets("Maria").Range(Cells(30,10)).Select

If it still doesn't work, put this before your select  statement:

MsgBox Activeworkbook.name & chr(13) & activeworksheet.name

This should show you the name of the workbook and worksheet before you select
the data...

It has to be something that you're doing before you get to this point.