I rarely use **VBA Access** for maintaining our legacy application. I am using **MS Access 2007**. I am trying to use tri-state in a text-box input. In other words, I have a textbox input that is bind to Boolean field (HOME which is bit with allow NULL in SQL Server) in database; however, I need to show `1` not `-1` for `true` when user enter `1`. Similarly, there should be `0` for "false" when user enters `0` in database. The last case is: it should save `Null` in database if user enter nothing or space.
What I did so far:
Under Property Sheet for this textbox:

1. Under `Format` tab, I set `Format` field to nothing instead of true/false, on/off or yes/no as I need three state.
2. Under `Data` tab, bind `Control Source` to `Home` field.
3. Under `other` tab of property, I set `Status Bar Text` to `1=HOME, 0=Not HOME`

Problem :  

1. When I enter `1`, textbox is displaying `-1` and it saves `1` in table which is good.
2. When I enter `0`, textbox is displaying `0` and saving `0`. So, this case is good.
3. When I try to enter nothing or space, it takes `0` by default.

Can anyone please tell me how do I achieve the three state for my Boolean text-box? or redirect me to the link here in Stack Overflow because I couldn't find one when I was researching in SO.