Dear Sir,
I recommand you to download and install the Service Pack 2 of Advance Steel 2011 as the Service Pack 2 improves the management of user modifications done directly on the drawings before the automatic update completes.
You can download this Service Pack 2 at Downloads > Service Pack > Advance Steel on the GRAITEC Advantage website.
I also recommand you the apply the recommandations explained in the FAQ "What are the supported snap points for manual dimensions" ; here is the link to get this FAQ: http://www.graitec.com/en/FAQ_view.asp?FAQID=968&Language=EN&Name=What+are+the+supported+snap+points+for+manual+dimensions+%3F
Regards / Philippe