请问大家！STALL现象

在读操作过程为什么会总少2个包（不管包的大小）后得到STALL？

我是对U盘进行读写操作，读朗科的16M盘会出现以上现象，32M，64M的却OK，我搞不明白。

Can you make it more clear?
老兄你能不能回答我的贴子啊?
\"HELP!!! 关于USB CF读卡器\"
我也碰上了你以前类似问题.
已经困扰了2个星期了.
如蒙指教, 不胜感激!!!
能不能电话联系?
 :)
Details:
Subject - Why I get a NAK??? Posted by Kelvin on June 19, 2002 at 22:33:52:
Hi, all:
I am developing a USB CF card Reader/Writer device driver on DOS platform.
The chip is GL641USB(Genesys Logic, Inc). I can dump device and configuration descriptor correctly.
I also set configuration correctly.
GL641USB is a Mass Storage Device (Bulk Only, SCSI Transparent Command Set).
I developed UHCI (VIA\'s chip) driver by myself.
My question is:
When I send a command (like Read_10) to the device for the first time, I can get data correctly (CBW->DATA->CSW). CSW shows that the command was invoked without error.
But when I send a second command (like Read_10), CBW is no error, data section got a NAK error, no data is transferred.
These two commands are of same opcode and same parameters.
Whichever command I send to device, it can be invoked correctly for the first time. But I get NAK in data section for the second time.
I have checked that there is no STALL or SUSPEND.
I don\'t know what is going on. The device can work well in Windows2k. Is my UHCI driver wrong, or device driver wrong?
Is there anyone who can help me?
Thanks in advance.




[编辑 -  6/21/02 by  kelvin9230]

大家帮帮忙！提提看法。