The component InterfaceQDV.dll comes with QDV7 in its installation directory. This component requires several other assemblies which also come with QDV7 in its installation directory.
The simplest solution is to install QDV7 on the machine which runs the DLL component so that you ensure that all requested files are there.
If you don't want to install QDV7, you must copy the following files to your directory:
▪InterfaceQDV.dll
▪Qdv.CommonApi.dll
NOTE You may have to update regularly your files by copying them from newer versions of the product. If you install QDV7 as usual, just run it once upon a time to have those files updated thru the update process of QDV7.