dear sir,
kindly every time i try to make a bolted connection, i get an error from design accelerator telling me: invalid thread data table, please check thread.xls file
 
any help please????????????

XLS is an Excel file so make sure there is nothing wrong with your Excel file.

I have never had that problem before. I would ask the same question on the official Autodesk forum: http://forums.autodesk.com/t5/Autodesk-Inventor/bd-p/78

dear sir,
how can i make sure that the exel file is ok, i've already tried to set it up on other computer but the same error happened to me, so how can the same error happened on two different machines.
do you think that the antivirus is related to this???????????????????????

I do not really know - I have never had that problem before. I can tell it is an Excel issue because .xls means Excel, but I do not know the exact problem. You should ask the Autodesk Inventor support people in this forum:

http://forums.autodesk.com/t5/Autodesk-Inventor/bd-p/78

I sometimes have a problem creating a bolted connection using an existing hole (using "concentric" placement) . Thanks for helping...