SIM800DS TCP question

[chamod]

I've been working on a weather station project, and I used a SIM 900 module to upload the data to a web server.
 Recently I started using a SIM800-DS for the same purpose. There wasn't much documentation on the module, but I managed to get a hardware design reference  and an AT command reference after contacting the manufacturer. According to the documents the module mush have the SIMCOM http stack but it didn't respond to any of the http related AT commands.
I realised I was stuck with a crippled firmware so I had to rewrite the code without using the simcom HTTP stack. Here I ran into a problem with get request.

After configuring the module and connecting to the internet, I opened a TCP connection using

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AT+CIPSTART="TCP","requestb.in","80"
And then, after sending

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AT+CIPSEND
I formed a simple GET request

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GET /s64y13s6 HTTP/1.1
HOST: requestb.infollowed by a 0x1a to indicate end of data. (I used requestb.in to test the requests).

The module responds with a SEND OK. But doesn't display the server response. ("ok"). After a while, I get this request time-out message.

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HTTP/1.1 408 Request Timeout
Connection: close
Server: Cowboy
Date: Tue, 05 Jan 2016 20:05:07 GMT
Content-Length: 0
It's unclear to me why this happens. (All the servers i tried either didn't respond or responded with a time-out. Should I do something more to indicate I've completed the request?
Here's a link to my stackoverflow question. (unanswered) http://electronics.stackexchange.com/questions/209672/sim800-http-get-request-time-out