Issues with file upload in flex mobile application (sharepoint as backend)

Hello,

I am working on flex mobile application for android platform for which we are having sharepoint as a backend.

(Flex SDK 4.6 and AIR 3.9)

Issue which we are facing is as follows:

We are communicating with the backend server using webservices: example:

<s:WebService id="kWebService" wsdl="http://www.kservice.net/kdatabaseservice.asmx?WSDL" >

            <s:operation name="AddPost"

                         resultFormat="object"

                         result="addPostResult(event)"

                         fault="postsfaulterr(event)" />

</s:WebService>

Above services are working fine but we are facing issue with one service which is related to file upload.

File upload for <10 MB is working fine but when we try to upload larger file on server it fails to process.

We are sending bytearray to the backend and backend code is writing those bytearray into file.

We have tried many ways to overcome from this situation. like we have checked configuration for file upload size on server , we have tried wcf services as well. Please help us on this criticle point as soon as possible

Thanks

Dhwani