unable to locate Pinpad (Pinpad320)

We are trying the Moneris Cloud based payment from a Pinpad320.  But it can't get through. 

(We use .Net MVC C#)

1:  reboot the pinpad,  it will get to the screen showing the pairing token number

2: then  we do a post for pair function from ajax,  the pinpad will change to show "Please Wait..",

   and finally it will show "Welcome/Bonjour"  in the Scrren.   

   It seems the pair funtion works fine.   While there is one thing we are not sure it is correct or not.

   in postback url, it does come to the postback, but we can get nothing there.  

   What are supposed to be sent back to merchant side from moneris? how to get that info.?

 

3. After pairing done, we a purchase function from ajax.  I think the Pinpind should prompt to pay and

   then we can insert the credit card,  but nothing happens in pinpad.

    the ajax post seems work successfully.

     And also after purchase post,  it does raise the post back url. but the same to #2,  nothing we 

     get from there.

 

by the way, if we perform pair or purchase in the back end (MVC controller) in stead of the ajax post,

and then get the response from the back end right away,  the response info. will be like below:

for Pairing function:

 {"receipt":{"ResponseCode":"001","Message":"Transaction request received","Completed":"false","Error":"false","TimedOut":"false","PostbackUrl":"https://xxxx/action/paircallback","CloudTicket":"ab575ffc-1baf-483e-bcb4-b6db0e545730"}}

 

for purchase function:

 {"receipt":{"ResponseCode":"903","Message":"Unable to Locate Pinpad","Completed":"false","Error":"true","Timeout":"false","PostbackUrl":"https://xxxx/action/purchasecallback","CloudTicket":"c50cf3d4-a9c3-46d5-91a3-452fc8d173f7"}}

 

so from the above response, it seems it can' find the pinpad to continue the payment.

 

Does anyone have any idea about this problem?

 

 Thanks