referencing an assembly in subdirectories

[Stefan Rosi]

Hello I've developed a custom control and compiled it to
"/controls/bin/Controls.dll".
When i try to reference this control from a page located in another
directory (like "/forms/default.aspx") using the following directive
<%@ Register TagPrefix="CusControls" Namespace="MyNameSpace"
Assembly="Controls" %>

I get an error message telling me that the assembly "Controls" was not
found.
How can I solve this problem ?
P.S. I can't move the assembly "Controls.dll" to another directory coz I
have some .ascx files in "/controls" using it.

Thanks in advanced