DIA Newbie compile problem

[Ron Harwood]

After I've done a ./configure (and that all works) I try to run make - 
and get the following (after a bit).

dia_xml.c:23: tree.h: No such file or directory
make[2]: *** [dia_xml.o] Error 1
make[2]: Leaving directory `/usr/src/dia-0.84/lib'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/usr/src/dia-0.84'
make: *** [all-recursive-am] Error 2

Any ideas what I may be doing wrong?