Causing another application to copy data to clipboard

I'm trying to programmatically make an external WinForms application copy its data to the clipboard, and it's driving me crazy.

Since pressing Ctrl-C in the application does the right thing, I've been trying to send ctrl-c using my C# application to the other application.

Here is my sequence of commands. I compared the messages using Spy++, and it matches except for my SendMessages are showing up as Send and Receive, vs. the same operation done on the WinForm is showing up as posted.

My code :

          NativeMethods.SendMessage(hwnd, WM_KEYDOWN, 0x00000011, 0x001D0001);
          NativeMethods.SendMessage(hwnd, WM_KEYDOWN, 0x00000043, 0x002E0001);
          NativeMethods.SendMessage(hwnd, WM_CHAR, 0x00000003, 0x002E0001);
          NativeMethods.SendMessage(hwnd, WM_KEYUP, 0x00000043, 0xC02E0001);
          NativeMethods.SendMessage(hwnd, WM_KEYUP, 0x00000011, 0xC01D0001);

Spy++ auto Run ->

 0059043C P WM_LBUTTONDOWN fwKeys:MK_LBUTTON xPos:322 yPos:54 [wParam:00000001 lParam:00360142]
 0059043C P WM_LBUTTONUP fwKeys:0000 xPos:322 yPos:54 [wParam:00000000 lParam:00360142]
 0059043C P WM_KEYDOWN nVirtKey:VK_CONTROL cRepeat:1 ScanCode:1D fExtended:0 fAltDown:0 fRepeat:0 fUp:0 [wParam:00000011 lParam:001D0001]
 0059043C P WM_KEYDOWN nVirtKey:'C' cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:0 fUp:0 [wParam:00000043 lParam:002E0001]
 0059043C P WM_CHAR chCharCode:'3' (3) cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:0 fUp:0 [wParam:00000003 lParam:002E0001]
 0059043C P WM_KEYUP nVirtKey:'C' cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:1 fUp:1 [wParam:00000043 lParam:C02E0001]
 0059043C P WM_KEYUP nVirtKey:VK_CONTROL cRepeat:1 ScanCode:1D fExtended:0 fAltDown:0 fRepeat:1 fUp:1 [wParam:00000011 lParam:C01D0001]

My Spy++ sequence :

 0059043C S WM_LBUTTONDOWN fwKeys:MK_LBUTTON xPos:299 yPos:52 [wParam:00000001 lParam:0034012B]
 0059043C R WM_LBUTTONDOWN
 0059043C S WM_LBUTTONUP fwKeys:MK_LBUTTON xPos:299 yPos:52 [wParam:00000001 lParam:0034012B]
 0059043C R WM_LBUTTONUP
 0059043C S WM_KEYDOWN nVirtKey:VK_CONTROL cRepeat:1 ScanCode:1D fExtended:0 fAltDown:0 fRepeat:0 fUp:0 [wParam:00000011 lParam:001D0001]
 0059043C R WM_KEYDOWN
 0059043C S WM_KEYDOWN nVirtKey:'C' cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:0 fUp:0 [wParam:00000043 lParam:002E0001]
 0059043C R WM_KEYDOWN
 0059043C S WM_CHAR chCharCode:'3' (3) cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:0 fUp:0 [wParam:00000003 lParam:002E0001]
 0059043C R WM_CHAR
 0059043C S WM_KEYUP nVirtKey:'C' cRepeat:1 ScanCode:2E fExtended:0 fAltDown:0 fRepeat:1 fUp:1 [wParam:00000043 lParam:C02E0001]
 0059043C R WM_KEYUP
 0059043C S WM_KEYUP nVirtKey:VK_CONTROL cRepeat:1 ScanCode:1D fExtended:0 fAltDown:0 fRepeat:1 fUp:1 [wParam:00000011 lParam:C01D0001]
 0059043C R WM_KEYUP

You could use PostMessage

Or try SendInput, although then you have to give the target window the focus first.