Unable to cast COM object of type 'System.__ComObject' to interface type 'Acrobat.AcroAVDoc'

I'm unable to load a PDF in WinForms.

Here are the DLLs I'm referencing:

• AxInterop.AcroPDFLib.dll
• Interop.Acrobat.dll
• Interop.AcroPDFLib.dll

Here's my code:

Acrobat.AcroAVDoc oAvDoc2 = null;

oAvDoc2 = (Acrobat.AcroAVDoc)Activator.CreateInstance(Type.GetTypeFromProgID("AcroExch.AVDoc"));

I'm receiving the following error:

Unable to cast COM object of type 'System.__ComObject' to interface type 'Acrobat.AcroAVDoc'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{9B4CD3E8-4981-101B-9CA8-9240CE2738AE}' failed due to the following error: Library not registered. (Exception from HRESULT: 0x8002801D (TYPE_E_LIBNOTREGISTERED)). | System.InvalidCastException