frind assembly with the odd error

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C#

C#4.0

i have trouble with building some projects. please consider this scenario:

i have 2 projects. for example A and B.
there is a reference from A to B
project of B was strongly signed (i did not want it to be signed for some reasons. so i decided to remove it`s checkbox of "sign the assembly")

there was a line of code in AssemblyInfo.cs file in the A project says:

[assembly: InternalsVisibleTo("B,publicKey=0024......")]

i changed it to:

[assembly: InternalsVisibleTo("B")]

now when i compile one of these projects, an error has came up and says:

Friend assembly reference 'B' is invalid. Strong-name signed assemblies must specify a public key in their InternalsVisibleTo declarations.

my question is here: how does compiler know that it was a signed assembly someday? and how can i completely remove strongly signed from assembly of B and finally build them correctly?

edited: by the way please note that both of theme is not strongly signed! because i remove both of those "sign the assembly" checkboxes from those project`s properties

when i changed the name of assembly to the some wrong name like "bla_bla_bla" that does not even exists, the error is the same!
[assembly: InternalsVisibleTo("bla_bla_bla")]
i think that this Theory is true:
in fact B Project does not compiled, and if it does not find the matched compiled project name (when building project A), compiler guess that B project is strongly signed with the public key that developer did not provide it! and at last it will prompt such odd error!
for the reason of B has a reference to A, when i compile B project, it will compile it's reference first (A project) and again compiler will prompt me that error (as the same as when i comopile project A)

but either it`s not true or some thing is wrong with my project A. because i start two new simple projects from scratch and every thing goes fine with no error (even when i change [assembly:...] statement to the invalid assembly name) i completely crashed