The DropDownList is incorrectly marked as invalid, when another field of the model is invalid.
Sample project attached.
MVCFormValidation.zip
Two validation errors appear after the form submission: one for the NumberOfShares field and a second one for the Country.Id field, for which a DropDownList editor is used.
A validation error appears only for the NumberOfShares field.
Note that if no editor is specified for the Country.Id field (instead of using a DropDownList editor), e.g.,
i.Add()
.Field(f => f.Country.Id)
.Label(l => l.Text("Country"));
no validation error message is shown for Country.Id.