Add a User Control to another UserControl in Web Application

[J0ker]

I am writing a Web Application in asp.net 4.0.I have a Solution say ControlLib, where a have my User Control UC_A.I have another Solution say MainLib, which contain a User Control UC_B.I have added the .ascx,.dll and pdb file of my ControlLib to my MainLib.Now a have to use UC_A in UC_B.Please tell me how can i achieve this.Thanks in Advance