Why I am getting exception "Cannot Find Original Sender" while verifying a signed certificate?

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C#3.5

signature

Why the exception "Cannot Find Original Sender" is coming on verifying a signed certificate?
I am verifying a digitally signed certificate using signedcms. But on calling the method CheckSignature I am getting the exception "Cannot Find Original Sender".

Digital Signature Verification Code is as below:

ContentInfo contentInfo = new ContentInfo(msgBytes);
//  Prepare an object in which to decode and verify.
SignedCms signedCms = new SignedCms(contentInfo, true);
signedCms.Decode(encodedSignedCms);
signedCms.CheckSignature(extraStore, true);