Value does not fall within the expected range. But the field exist

Question

I have the following problem. I have a list with a custom content type, when programmatically I want get an information from my SPListItem I get the following exception: Value does not fall within the expected range.

If I print all the fields of my item I have the field I looking for. I try to get the data by the GUID, by the internal name and so on, but I receive always the same error.

Why?

    private static DateTime GetModified(SPListItem item)
    {
        // I tried it
        //string ultimarevisione = item.GetFormattedValue("MyCustomField");
        if (item[new Guid("{EA440C5B-845D-482F-8D10-666B06851AFE}")] == null)
            return DateTime.Parse(item["StartDate"].ToString());

        return (DateTime)item[new Guid("{EA440C5B-845D-482F-8D10-666B06851AFE}")];
    }

    var field = item.Fields.GetFieldByInternalName("MyCustomField");

    //in this way doesn't work too
    if (item[field.Id] == null)
            return DateTime.Parse(item["StartDate"].ToString());

I got it with a LINQ query

var results = docs.ScopeToFolder(docsList.RootFolder.Url, true)
.Where(p => p.ItemType == SPFileSystemObjectType.File &&
p.ItemType != SPFileSystemObjectType.Folder)                                                                                             
.OrderByDescending(d => d.Modified);

Answer 1

Try to open your List/Item with Sharepoint Manager tool and check exactly what is the correct internal name of your field.

Answer 2

How do you get this SPListItem in the first place? For example, when item is retrieved by CAML query without necessary fields defined in ViewFields section, it may lead to exception when retrieving such a field.

Answer 3

I think that you get SPListItemCollection from SPView, but this SPView does not contains needed field