Error "Metadata error not found" when linking to an assembly in T4

Question

I have a class Alibrary and a library Bwith a T4 template.
B links A and the assembly directive exist inside the template:

<#@ assembly name="$(ProjectDir)$(OutDir)A.dll" #>

When a template conversion error is triggered, it displays:

Transformation compilation: metadata file: 'path \ A.dll' could not be found.

But this file is!

I get this error in VS 2012.

I do not know what causes this error.

Update

Well, I found an error in the build directive, I just made a mistake.