This is a known issue with Check Boxes and Web Direct.
For More Information see: WebDirect Bug - values for Radio and Checkbox Buttons display as row , not as list
This is one of many acknowledged bugs that can be found in the Known Bug List thread here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: https://www.dropbox.com/s/jt09b82i0xijbu3/FMP%20Bugs.zip
thanks for helping
but i am still confused that how could i use known Bugs list to fix that problem
is there any file that i could download it ?
The known bugs list doesn't fix them, it's a means to confirm (or not) that the issue you encountered is known to FileMaker tech support. If you click the link provided there can sometimes be a work around found in the issue report that I linked to the Known Bugs list.
I seem to recall some discussion of work arounds in that thread, but maybe my memory is faulty.
You may be able to resolve this issue by redesigning your layout. You can, for example, put multiple copies of the same field on your layout and set up each with a different value list of just one or two of the values shown. That's a lot of work just to get a check box group working but it might be one approach to a solution.
Another option might be to use a portal to a list of records where you have one record for each check box value. Clicking a button in the portal row--which can cover the entire portal row, selects that value just like clicking a check box and a second click can remove the value just like a check box.
Here's an older file format demo file of this method: https://www.dropbox.com/s/ti8vep64h67mtj2/CheckboxWScrollBar.fp7
You can use Open from FileMaker's File Menu to open this file and produce a copy converted to the newer file format.