【求助】VB向百度贴吧POST发帖时的错误。

发送按钮事件代码：

Dim myurl As String
Dim send_data As String
Dim my_head As String

myurl = "http://tieba.baidu.com/f/commit/thread/add"

send_data = "kw=f1&ie=utf-8&rich_text=1&floor_num=0&fid=66&tid=0&mouse_pwd=123%2C114%2C125%2C102%2C120%2C122%2C122%2C122%2C67%2C123%2C102%2C122%2C102%2C123%2C102%2C122%2C102%2C123%2C102%2C122%2C102%2C123%2C102%2C122%2C102%2C123%2C102%2C122%2C67%2C121%2C122%2C126%2C125%2C123%2C114%2C67%2C123%2C121%2C124%2C124%2C102%2C125%2C124%2C114%2C13286780680741&mouse_pwd_t=1328678068074&mouse_pwd_isclick=1&title=aa111111111111111111111111111111111111111111&content=222222222222222222222222222222222222222222222&anonymous=1&tbs=bc7be7745a1c45201328678063&vcode=" + Text1.Text + "&vcode_md5=" + vcode_md5

my_head = "Content-Type: application/x-www-form-urlencoded"
Inet1.Execute myurl, "POST", send_data, my_head


发送不成功，得到返回如下：
{"no":13,"error":"","data":{"fid":66,"fname":"f1","is_login":1}}
求大侠们帮忙啊 tbs的值是动态变化的。

补充：VB ,  网络编程