Your greenhouse is designed to be weather tight. The installation instructions have specific details on how to properly seal the roof.
The installation instructions have specific details on how to properly seal the roof. Sometimes this step has been missed. Please check the roof to ensure that silicone sealant has been applied where the cap meets the glazing at the top and bottom of each panel.
If the sealant has been applied, please refer to the instruction manual to ensure that all places have ben sealed and caulked. If installation happens on a dry day, some places could be missed.