A little more information would be useful! What version of MEP? What are the OS and specs of your computer?
A very quick look at the product page for that interface suggests strongly that it needs some kind of "cable" input connection. (The input connector is very similar to/the same as those I've seen used in the UK for satellite or digital cable TV feeds.) So, presumably, you are trying to "record" an incoming TV feed?
Or, are you trying to import to MEP a file recorded by one of the softwares on the Hauppage page in order to "edit" it? A quick read of the web site information suggests that the native recording format for this software is MPEG-2. I think this should open properly in MEP but there MAY be somekind of proprietary protection built-in. The free MediaInfo and/or GSpot will supply information about the codecs needed to play the file. However, if the format is in some way "protected" you may not be able to successfully import it to MEP.
Jeff
Update: having just re-read your original post I see you are trying to import from a VCR. I think this may not be possible because the input to the interface is clearly coaxial (which is, I believe, one particular format) and the output of your VCR is most likely either RCA Phono, SCART, or S-Video (or a combination of these) each of which is a different format. I know some format convertors are available (they work as "in-line" devices between the output of your VCR and the input of your interface) but how "good" they are or how much they cost or whether they would work in this scenario I really don't know.
Thanks for the info. I have a VCR with coax output (select channel 3 or 4). I am feeding the Hauppauge directly using a coax cable. I am using the downloaded version of "MAGIX Movie Edit Pro Plus Download Version" Version 11.0.1.4(UDC2). When I press the "Record" button and select "Video", the section 1 "Video Drfivers:" has the entry "WinTV HVR-950 Capture (USB - ..." greyed out. After a few seconds a pop up says "Could not connect to selected device".
You should be able to record from the RF (coax) output of your VCR but you will need to set up everything (MEP and HVR) as though you are recording from an aerial (analog TV) signal. Surely though your VCR has AV outputs which can be connected to the 950 side AV input via the special cable supplied which would be much simpler.
It sounds however that your HVR950 drivers are not properly installed on your PC. Can you record via the WinTV software and an aerial connection at all? Try reinstalling from the software disc that came with the HVR.
There is also a separate Magix PVR software called "Video recorder" under Magix > MEP17> Video recorder, that has a settings button bottom right which give access to the advanced (Tuner) settings where you would configure the RF signal input. Please read the Help contents in MEP under Video recorder.