Specialized utilities for Symbian phones like the SIS to JAR Converter can be used to convert various Symbian app installation packages (.sis, .sisx, .jar) between each other so they can be used on different versions of Symbian. However, .jad files are just app descriptors and do not contain the actual app, they may be generated alongside the .jar file, but unlikely directly from a .sis file.
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.