A very likely cause is that the filter you've registered is not the same architecture as the version of GraphEdit.
Both GraphEdit and filters come in 32bit and 64bit flavors.
If you registered (successfuly) a 32bit filter it will only be available to 32bit DirectShow applications, which includes the 32bit GraphEdit. This filter won't work with and will not show up in the list for the 64bit GraphEdit.
The reverse is also true: 64bit filters only work with 64bit DirectShow applications.
So, make sure that you're using the matching architecture version of GraphEdit to your filter.
Of course, if you're registering the filter make sure that the operation is indeed successful!
The most popular reasons filters fail to register are:
- permissions: make sure to run
regsvr32
as admin
- dependencies: make sure all DLLs the filter depends on are present on the system, in the search path