digest_mismatch - Part digest was incorrect

We are trying to implement Chunk Upload Feature.
SHA1 is being generated for each chunk, but when we post it to the Box Api, It throws the error "digest_mismatch - Part digest was incorrect"
SHA1 is created for each chunk. But we are getting the below response from the upload api (https://upload.box.com/api/2.0/files/upload_sessions/DB0ED4E4961D3F30D824FB3A09014B4F) : 

{"code":"digest_mismatch","message":"Part digest was incorrect. Actual: WD3JpnRmM79ZmFmdJvfBTdr8lu0= Expected: 2jmj7l5rSw0yVb/vlWAYkK/YBwk=","request_id":"00f0b572f06c5af6c26170b0203fc149"}

Any help will be appreciated