You do not offer enough information for anyone to know for sure, since you  
didn't include anything that would tell us for sure what the type of "dt"  
is, what type its Rows property is, or how the Count property is to be  
used.

However, if it's anything at all like other classes, the Count property is  
read-only and you cannot assign anything to it.  If you want to change the  
number of elements in the Rows collection, you need to do so by adding or  
removing items.  It's certainly possible to design a class that would do  
that for you when you assign a value to the Count property, but it would  
be a bad idea and I hope there aren't any .NET classes that do that.

Pete