How to share a Cancellation Token with two DLL?

Question

I've the following code in a FIRST dll :

public Task FuncAsync(string a, string b, CancellationToken ct)
{

    Task t = new Task
        (
            () =>
            {
                Save(a, b, ct);
            }, ct
        );

    t.Start();
    return t;
}

private void Save(string a, string b, CancellationToken ct)
{
    classA.func(a, b, ct); // DOESNT WORK !
    //classA.func(a, c);     // WORKS !
}

The method class classA is in the SECOND dll :

public void func(string a, string b, CancellationToken ct)
{
// some code...
}
public delegate void ProgressHandler(object sender, ProgressArgs progressArgs);
public event ProgressHandler ProgressChanged;

Then, my method FuncAsync is called in a Console Application :

CancellationTokenSource cancelSource = new CancellationTokenSource();
CancellationToken ct = cancelSource.Token;
Task task = B.SaveAsync("", "", ct);

The first DLL include the second, the console application include the first DLL.

This code compiles fine, no warning, no error. But on execution, error on the line : Save(a, b, ct);

Additional information: Could not load type 'ProgressHandler' from assembly 'A.B.C, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' because the method 'func' has no implementation (no RVA).

If I delete the CancellationToken from the code, all is ok.

How can I send my CancellationToken from the Application to the DLL1, then from DLL1 to the DLL2 ?

EDIT :

I forgot to precise that I merge the two DLL in one only with the command :

ILMerge /target:libray dll1Temp.dll  dll2.dll  /out:dll1.dll  /internalize /allowDup /lib:C:\Windows\Microsoft.NET\Framework64\v4.0.30319
del dll1Temp.dll
del dll2.dll

When I don't merge the library, there are no error in my code.