Validate File Mimes Types Trouble

I'm having trouble validating file types. Even though I've used dd($mimeType) to confirm that my file type is correctly application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, when I try to upload the file, it still fails validation ($validator->fails()). Can anyone offer any advice, here is my code

        $file = $request->file('file');
        $mimeType = $file->getClientmimeType();
        $validateArr = [
            'file' => 'mimetypes:application/vnd.ms-excel,application/vnd.openxmlformats-officedocument.spreadsheetml.sheet,application/octet-stream'

        ];
        Log::info('Import Create Intent Evaluation : Mime Type 1 : ' . $mimeType);
        $validator = Validator::make($request->all(), $validateArr, [
            'file.mimetypes' => 'Chỉ hỗ trợ file có định dạng .xls, .xlsx'
        ]);
        dd($mimeType);
        if ($validator->fails()) {
            throw new ValidationException($validator);
        }