I have inserted some objects in my sheet (combo box, option buttons)

This code works perfect:
ActiveSheet.OLEObjects("CBoxConc").ListFillRange = "ProdProductos"

But this one returns an error 438:
ActiveSheet.OLEObjects("CBoxConc").Text= "MyText"

This one returns an error 438 too:
ActiveSheet.OLEObjects("CBoxConc").List Index = 1

Any help or suggestion???

Thanks in advance !