Cinchoo.PGP throwing null reference error when all references are valid - c#-4.0

Question

I am using Cinchoo.PGP to decrypt some files. When it runs, I am getting an "Object reference not set to an instance of an object" error.
using (ChoPGPEncryptDecrypt pgp = new ChoPGPEncryptDecrypt())
{
EncryptionViewModel pem = rpt.Encryption_In;
var from = setFiles.FileToProcessPath + setFiles.FileToProcess;
var to = setFiles.ProcessedPath + setFiles.ProcessedName;
if (from == to)
{
to = setFiles.ProcessedPath + "_" + setFiles.ProcessedName;
pgp.DecryptFile(from, to, pem.PEMPath, pem.PassPhrase);
File.Delete(from);
File.Move(to, from);
}
else { pgp.DecryptFile(from, to, pem.PEMPath, pem.PassPhrase); }
}
Stack trace is here:
at Cinchoo.PGP.ChoPGPEncryptDecrypt.Decrypt(Stream inputStream, Stream outputStream, Stream privateKeyStream, String passPhrase)
at Cinchoo.PGP.ChoPGPEncryptDecrypt.DecryptFile(String inputFilePath, String outputFilePath, String privateKeyFilePath, String passPhrase)
at EDI2.Data.Process_Unencrypt_File.Process(ReportAllDataViewModel rpt) in C:\TWRAProjects\EDI2\EDI2\Data\Data_Process.cs:line 544
When I step through the code, all my variables are correct. My files exist, the pgp reference is valid, my "from" file exists (I manually verified that), my "to" file doesn't exist (same), and my PEMPath and PassPhrase values are populated.
When it runs the pgp.DecryptFile line, however, it throws the "object reference" error.
I'm not sure if I've found a bug in Cinchoo.PGP, or if I am doing something wrong. Anyone have any thoughts? Has anyone else experienced this?
Thanks,
Carthax