Good -- never use SQL Authentication as this exposes a serious security threat.
The problem is with the login you created on SQL Server.
- start SQL Server Management Studio (SSMS)
- expand branch Security
- create a login named "IIS APPPOOL\ICOGZIMBRA"
Don't select it from the user account selection window, just type in the name as shown above without the quotes.
- at the left, select tab "User Mapping"
Select the database that this user account has access to -- just check the selection box at the front.
SSMS will auto-create the appropriate database user and map it to this login.
You are using Integrated Security, aren't you?