Transmitting Frequency

I am working on a project for a class, and we have been using the FM
transmit functions included with the examples, and we’ve run into a
problem
where we are unable to transmit on frequencies from about 40 to 80 MHz,
the
problem is that we would like to transmit at 72MHz. The errors amount
to
something like “cannot tune frequency”, etc… Does anyone have any
suggestions as to how we might get this to work?

Thank You,
Scott Meuleners