MC limits the amount of intraday data when setting the date range using the N Bars Back option to 91 days of data.   This is to, "avoid overloading the datafeed with excessive requests (necessary when the datafeed does not provide this much of historical data)".
 
So if you are using 60 or 120 etc. minute charts, you can only go back a couple hundred bars.  Many strategies require more than this to generate trades. 
 
I want to be able to load the minimum amount of data to avoid bogging down my computer.  The current MC recommendation is to use a data range, but this is not a good solution because the start date is anchored and therefore, every day you are loading more and more data.  One could achieve the same effect by "rolling" the start date up every once in a while, but if you use 30 or more charts like me, this can be a lot of work.
 
It seems silly to institute this limit when instead MC could simply add logic that says, "IF there is insufficient historic data to meet the user's request THEN do not send repetitive requests...".  Or, something to this effect.
See thread here:
 
http://www.multicharts.com/discussion/viewtopic.php?f=1&t=11345&sid=58048a3987539e7d14b30e91a5f2d0ff&p=56024#p56024