Custom DLL for solution not deployed to GAC

Hi, my solution has 2 projects.

1. Company.UI - this contains all the ascx code for the web parts
2. Company.BLL - this contains all the logic and code between the web part and MS SQL

My issue is this, in one of the ascx file in the Company.UI, i tried to create an object to reference to the class. eg: UserBll myBll = new UserBll(); when i deploy the code and tried to view the web part. i receive the following error on the browser : File not found".

unable checking my logs i saw the following error

System.IO.FileNotFoundException: Could not load file or assembly 'Company.BLL, Version=1.0.0.0, Culture=neutral, PublicKeyToken=22960a56b5bxxx' or one of its dependencies. The system cannot find the file specified

C:\Windows\Microsoft.NET\assembly\GAC_MSIL

i saw that only the Company.UI folder was created, Company.BLL wasn't created. could this be the cause? and how to fix this?