want to use the thumbail function explained elsewhere in the forum. When I write this expression in the formula field

"<img src='http://creator.zoho.com/DownloadFile.do?filepath=/" + <UploadFiledname> + "&sharedBy=<Username>' title='" + "' alt='" + "' width='64' height='75'/>"

save and then reopen the formula field editing window, the expression was cut to: 

"<img src='http://creator.zoho.com/DownloadFile.do?filepath=/"

the rest of the expression was completely deleted and therefore the thumnail function does not work...

Also, how can I make the thumbnail work as an HTML link to the larger image?

thanks in advance