Strategy ELA help

["bkmk" <bkmk@xxxxxxxxxxxx>]

I have a chart in which I plot a stock in subgraph 1.  In subgraph 2, I
have 2 indicators plotted.  One is scaled the same as the symbol and one
is scaled to the screen.  The 2 indicators have different ranges (55-60
-same as the symbol and 4550-4700).  I would like to write a strategy in
which I buy when one indicator crosses over the other.  Can this be done
if they're scaled and range differently?  Just writing:  

If Indicator1 crosses over Indicator2 then buy at open;

obviously doesn't work.

Thanks in advance.

Barry