VSE 8.8 is not supported on ePO 4.0, which is currently End Of Life. You'll need to upgrade to ePO 4.5 or above.
In the VSS 8.8 installation guide i read the following.You can use ePolicy Orchestrator 4.0, 4.5, or 4.6 to manage the VirusScan Enterprise 8.8
software. To include VirusScan Enterprise 8.8 in the list of products managed by ePolicy
Orchestrator, you must install the following VirusScan Enterprise extension .zip files (XXX is the
build number of the VirusScan Enterprise 8.8 software.):
EPO 4.0 ?
Sorry, my mistake - that's the VSE 8.8 Help extension that you're trying to check in, and this requires ePO 4.5 or later. The management and reporting extensions should still check in correctly.
Please note though that ePO 4.0 is still end-of-life