Hi Goeff
I also use DynaZip and Install Shield. I have found that you need to tell InstallShield that the DynaZip files are 'Self Register'. Put the files in your InstallShield project. Then right click on the files and then choose properties. Go to the tab where you can set the property as 'self register'.
Hope this helps.
In the End, we will remember not the words of our enemies, but the silence of our friends - Martin Luther King, Jr.