ExtractExistingFileAction.OverwriteSilently is not overwriting the files in a given directory

I have a solution for updating an application that uses the API DotNetZip (http://dotnetzip.codeplex.com/) for handling ZIP files. One method is to overwrite files in certain folders as follows.

ZipFile zipFile =ZipFile.Read(file);{foreach(ZipEntry zipEntry in zipFile){
            zipEntry.Extract(@"C:\IASD\CantinaEscolar",ExtractExistingFileAction.OverwriteSilently);}}

Where: @"c: \ SDA \ CantinaEscolar" is where are unzipped the files inside the zip (files).

Now, if the directory already contains a file with the same name that will be unpacked, the application is returning an error related to the file already exists in the directory.

System.IO.IOException:The file 'c:\IASD\CantinaEscola\nomedoarquivo.exe' already exists

OverwriteSilently This method should not override the unzipped files silently (without requesting user confirmation)?

Or: Is there any way to force this overwritten within the directory (-type f or something)?

If you possess any other tips on how to accomplish this task, I will be grateful.