In the editor, the script works fine, but in the build, no!

Hello! Need to work with files, implemented using ICSharpCode.SharpZipLib. There was a problem. In the editor, the script works fine and retrieves files, but in build script exits on using (ZipFile zf = new ZipFile (fs)). Help please!

 using (FileStream fs = new FileStream (filenames, FileMode.Open, FileAccess.Read))
 {
 
 _PP.StatusUpdate (String.Format ("Open file {0} ...", filenames));
 
 using (ZipFile zf = new ZipFile (fs))
 {
 
 _PP.StatusUpdate ("Read zip ..."); << ---- Do not proceed to this step