Access denied on adding another registry value

I have originally created the SOFTWARE\\Testing key a few days ago and I just tried adding another value called TDate to this key and got an "Access denied" message when I execute the RegSetValueEx function. Does anybody know why I'm getting this "access denied" error message?

EDIT: Found my mistake.. RegOpenKeyEx should be KEY_ALL_ACCESS NOT KEY_QUERY_VALUE. I guess I'm a little brain dead.

Code:

DWORD lpdwDisp;
    HRESULT hRes;
    HKEY hKey;
    char szTDate[40] = {0};
    int iDatasize;
    char szTemp[120] = {0};
    char szRegistryKey[128] = "SOFTWARE\\Testing";
    if(RegOpenKeyEx (HKEY_CURRENT_USER, szRegistryKey, 0, KEY_QUERY_VALUE, &hKey) == ERROR_SUCCESS)
    {
        iDatasize = sizeof ( szTDate);
        if(RegQueryValueEx(hKey, "TDate",
            NULL, NULL, (unsigned char *)& szTDate, (unsigned long *)&iDatasize) != ERROR_SUCCESS)
        {
           printf("Query failed, create the value\n");
            strcpy(szTDate, "11082005");
            hRes = RegSetValueEx(hKey, "TDate", 0, REG_SZ,(LPBYTE)szTDate,(DWORD) strlen(szTDate)+1);
             if( ERROR_SUCCESS != hRes)
        {
            FormatMessage( FORMAT_MESSAGE_FROM_SYSTEM, NULL , hRes, 0, szTemp, 80 , NULL);
            printf("%s\n",szTemp);
        }
      }
    }