You are right. Mine got accidently working after I compiled the project on a 32-bit computer. It was only working after the build. Inside VisualStudio itself I could not connect to the databse. But now I did found the solution.
Installing the "Microsoft Access Database Engine 2010 Redistributable", followed by the "2007 Office System Driver: Data Connectivity Components" solved the problem for me!
When VisualStudio is debugging it wants the 32-bit version of the ACE.OLEDB.12.0 provider, so you need both of them on your computer. When you stop debugging you get back into VisualStudio and the Database will look like disconnected again. Just refresh and he finds the right OLEDB provider. Some said it is not possible, but it does!
It's written on the forum below what steps you have to follow.
I agree with norman - go to SQL Server ( but add a little bit of ADO.NET for completness ).
We have lots of DB-Acad-.XSLx-CSV-and-you-name-it work plus x86 and x64 AutoCADs (even 32bit Acad on 64bit comp.) on different machines plus legacy code (!). If you add to the .NET-SQL tandem a little bit of ADO.NET 4 you are on the right direction.
From ADO.NET we get data from DWGs then we sort and consolidate and then we export to whatever we want ( ADO.NET has data providers for almost everything).
My choice after working for some years with MySQL+ODBC+ACAD is MSSQL+.NET+ADO.NET+OpenXML+ACAD.
Explore this link http://msdn.microsoft.com/en-us/library/ms971485.a
I haven't read all the postings in detail, but I found a way to install 64Bit ACE Engine on systems with 32 Bit Office.
Download AccessDatabaseEngine_x64.exe http://www.microsoft.com/download/en/details.aspx?
And install it via Command Line with:
> AccessDatabaseEngine_x64.exe \passive
Now you should be able to connect to Access DB Files even though it is 32 Bit and your environment is 64 Bit.
Just wanted to let you know that your repsonce here was very helpful to me too. I've been struggling with a suite of Access databases used over the past 10 years and now moving to .net to connect both 32bit and 64bit Acad to them. It's time to update the DB's before i can move forward. Again, appreicate your thoughtfull responce.