Hi,
This sounds very strange. As though the 'Install' button had its 'visible' property set to 'No' in the template *.ism file or something.
The way you can check this is to open the *.ism file in the AdminStudio Editor (AKA InstallShield), and locate the ReadyToInstall dialog in the Installation Designer -> Dialogs view, and make sure 'visible' is 'Yes' on this button.