I hear this problem occasionally. Customers have COM/DCOM component on the system registered properly, they want to enable DCOM on their component (to access the component over the network!). They need to modify the permissions for their component, for which they open DCOMCNFG.exe, but they can not find their component in the list of DCOM components installed.
If this is happening, mostly its the issue with AppID!
As I told in one of my previous post, DCOMCNFG is supposed to create AppID if its not already there! But, if it has happened that DCOMCNFG is not doing its task, first, please drop me a line, I want to debug that further and second, follow the alternate way to generate AppIDs properly.
Open OleView.exe (if you dont have it, download it from here). Expand "All Objects" by double clicking on it (it might take some time as its enumerating entire HKLM\CLSID and related keys,
Select your object from the expanded list. If your COM/DCOM component is registered properly, you should be able to find your component in the list! As you select the component, you will see right side pane with various options.
Select "Launch Permissions" tab, you should get something similar to below.
Select the radio button, "Use these launch permissions:". Clicking this setting is supposed to create the required AppID key. So, after you select this option, you can select the default launch option again (that would not remove the newly generated AppID!) and close the OLE Viewer.
Hope that helps..