I have an Installshield2010 project that has had this warning since before my employment
ISDEV : warning -3028: The string ID "IDS_ERROR_27555" was not found in the string table. It is referenced in the table:"Error" in column:"Message".
Looking in the svn history, this row was added to Error table a few years ago - alongside a seemingly unrelated change
<row><td>27555</td><td>##IDS_ERROR_27555##</td></row>
However as the error indicates, there is no corresponding entry in the ISString table. I'm curious how it got added. The IDS_ERROR strings look like canned strings, it seems really unlikely the person who added this to my ism did so manually.
Of course Flexera's forums are a ghost town. I did find an ism that has that string defined as
<row><td>IDS_ERROR_27555</td><td>1033</td><td>Error attempting to apply permissions to object '[2]'. System error: [3] ([4])</td><td>0</td><td/><td>1394414478</td></row>
Do any of your ism's have IDS_ERROR_27555 defined or referenced? Am very sure I can delete the string and be no worse for wear... but it bugs me to not know what happened.