Make sure that you are actually Digitally Certifying the document. Placing your professional seal or scanned signature in the document is not Digitally Certifying a document, these are just images and have no legal weight on their own when submitting to the OGPe.
Verify the information regarding the Digital Certificate from the document being submitted. Make sure that the document in question has been Digitally Certified with a correct and current Digital Certificate.
Here is a link to a manual that covers the necessary steps needed to determine whether the Digital Certificate is correct and current. Adobe Acrobat Reader X: Manual to Verify the Digital Certification of a Document
It is important that you keep your professional license up to date with the Board of Examiners (Department of State). If your professional license has expired, OGPe will reject your submission. Also, make sure the documentation being submitted has been delivered using the correct file format.
The following file formats should be accepted by the OGPe:
DWFx: plans can be submitted using this file format, with the exception of mensuration plans involving polygons.
PDF: Any document can be submitted using this file format, with the exception of mensuration plans involving polygons.
DXF : Mensuration plans involving polygons need to be submitted using this file format. DXF files are not to be Digitally Certified.