Thanks CEH and Missingling for your advices!
I´ve tested a lot of adjustments to make it function, but the most important things to do was some basic adjustments of the database which I will show here:
When you create and move a database or parts of it:
Adjustment of Default folder
Press the Microsoft-button
- Choose Access-buttons (Down to the right)
- -Choose Popular
- --Choose Creating Databases
- ---Choose Default database folder
- ----Browse to find folder where you have the Formpart of the database (if it is split into two parts)
Adjustment of connection between tablepart and formpart of the split database
- Open the database
- -Choose Database Tools
- --Choose Linked Table Manager
- ---Choose Always Prompt for New Location
- ----Choose Select All and OK
- Choose Folder with the Tablepart of the split database
Adjustments of ”Trusted Locations”
- Press the Microsoft-button
- --Choose Access-options (Down to the right)
- ---Choose Trust Center
- ----Choose Trust Center Settings
- -----Press Add New Location
- ------Choose the folder with the databaseparts. Press OK.
If you get a Security-Warning in the mainpage of the database, it can be a sign of not functioning database
Sometimes youcan loose important functions because of security reasons.
It could help you to press “Options” and choose “Enable this content”. But first you have to consider the security risk of “Enable this content”!