Morning everyone

I am trying to put 2 formulas into one cell but seem to be struggling, I am
sure this is simple and could really do with some help

A1 = 4
B1 = 12/02/2007
C1 = 08/03/2010

In D1 I am doing the following forumla (I am trying to get a result of 4:36)

=A1&":" + DATEDIF(B1,C1,"M")

I keep getting VALUE returned back not the 4:36 I am after

Any help appreciated

Thanks