Erlang not building is causing an upgrade problem

[Frank J. R. Hanstick]

Hello,
	When trying to upgrade via

		sudo port upgrade installed

erlang causes the upgrading to cease when failing to build.  Erlang is  
not installed (as recommended from the ticket); but, attempts are  
continuously made to install resulting in a failure to upgrade the  
entire installed list.  Under the current structure, it seems  
impossible to determine which port requires erlang (no list of  
dependencies provided at the beginning of each upgrade or installation  
in the debug listing).  Is there a way to get a dependency tree for  
installed ports?
Frank J. R. Hanstick
trog24 at comcast.net