Error with code.. i dont know why.. please help! (noob)

Hi there, I’m a applescript newbie and I’m having trouble with this line:

set marktitle1 to title of table column "mark1" of table view "datawindow" of scroll view "scrollview" of window 1 as string

It seems to give me this error every time I run it…:
“Can’t make «class titl» of «class tabC» “mark1” of «class tabW» “datawindow” of «class scrV» “scrollview” of window 1 of «script» into type string. (-1700)”

Can someone please help me with this? I’ve searched all over the web, and I’ve found nothing about anything like this. Why is it giving me this error?
Is it even possible to set a variable to the title of a table column?

Thanks in advance.