Report An Issue is intended for Reporting Possible Software bugs. Questions on how to work with FileMaker Pro should be posted in the FM Pro Forum Section. (See tab at top of this screen.)
Two things need to be set correctly in FileMaker. Did you set them?
Sharing must be enabled for the FileMaker Application that is being used to host the file.
Sharing must be enabled for the FileMaker File that you are trying to Host.
Both options are set from the same dialog. To enable sharing for the file select it in the open files list and then select the "all users" radio button.