You cannot exactly convert ZIP archives to ISO format. However you can create ISO compilation for burning that contains .zip archives. This can be nowadays done with any almost any ISO preparation tools. Otherwise it seems no ZIP to ISO conversion is possible.
This conversion entry was verified by us and conversion was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
If you find entry that you feel is flagged as bad wrongly, please tell us in the discussion below with as much as information as possible so we can fix it.