Having problems installing an agent on a machine where there was an agent previously installed?
Probably the most straightforward way of resolving this is to edit your agent install package and add a /r /w switch to it, which forces the package to install and overwrite over any existing agents that are already on the machine. To do this, in the Kaseya admin UI, click on Agent-> Deploy Agents. Click on the edit package icon beside the agent package you are using.
Then on step 3 of the wizard add your switches. For more information click on the Switch Definitions link. Then try reinstalling the agent on the machine using this agent package and it should install.