delphi开发天敏vc4000视频卡，XP系统4路画面正常显示，win7只显示1路，怎样解决？
procedure InitGlobalVar();
begin
//主窗口用到的全局变量
g_nCard :=0;
g_nCard1 := 1;
g_hWnd := HWND(0);
g_hWnd1 := HWND(0);
g_szVidSize.cx := 360;
g_szVidSize.cy := 288;
g_nCurVs := 0;
g_nFrameRate := 25;
g_strCurComp := 'XviD MPEG-4 Codec';
g_bBmp := False;
g_nPlayState := 0;
end;
procedure Connect();
begin
VCAConnectDevice( g_nCard, ToVcbool(True), g_hWnd, g_szVidSize, VIDEOSOURCE(0), g_nFrameRate,VideoSubType_YUY2);
VCAConnectDevice( g_nCard1, ToVcbool(True), g_hWnd1,g_szVidSize, VIDEOSOURCE(0), g_nFrameRate,VideoSubType_YUY2);
//全局变量更新
g_nPlayState := 1;
end;
