directinput dll problem

I'm developing an app in c# that uses directinput... in my dev pc, that there's installed directx sdk everything works fine... but in another pc that have only directx client installed, the app didn't work.. I added into the folder the dll:

• Microsoft.DirectX.DirectInput.dll

I need to add someother to let's play???

thanks in advance! the error is this:

Is not an application WIn32 valid (Exception from HRESULT: 0x800700C1)

this happens here:

        // Find all the GameControl devices that are attached.
        DeviceList gameControllerList = Manager.GetDevices(DeviceClass.GameControl, EnumDevicesFlags.AttachedOnly);

0x800700C1 is ERROR_BAD_EXE_FORMAT

http://technet.microsoft.com/en-us/library/cc782541(WS.10).aspx

I'm guessing you are targetting 64-bit windows and DirectInput is 32-bit only ...