I'm not sure I understand your problem. Soldat wouldn't run for you, so you reinstalled DirectX and now it runs again? Are you still having any problems?
The thread Elemental linked to was an issue that wouldn't allow Soldat to run due to problems with Soldat's advertiser, Monsoonix. If you're still experiencing trouble, you can try the fix found in that thread, although I believe the Monsoonix problem has been resolved.