Installing Xymon 4.2.3 on Debian

Hello,

I have an older version of hobbit running on a debian build at home (hobbit
4.2.0).

I have installed rrdtool using the apt-get.

However when I run the configure script I get

*RRDTool include- or library-files not found.  These are REQUIRED for
hobbitd RRDTool can be found...........*
**
Any ideas on where I can locate rrdinclude and rrdlib in debian 5.0.3?

Thank You,
Gary