Can't query access database using infopath over sharepoint

[Sherry]

I have created infopath forms to submit data into an Access database from
SharePoint, but the users get an error stating that cannot open the file 'x'.
It is already opened exclusively by another user, or you need permission to
view its data."
I have spent much time trying to find the solution, can anyone help me?
Thanks so much
Sherry