Firstly, make sure you have the transient (Time Dependant) checkbox ticked under General Settings>Analysis Type.
I believe this is because you are taking the previous results at t=0 (As in, time is 0 seconds, the initial condition from your first study). As such, you would expect the initial temperature to match the initial temperature from the first study. Are there no other time steps for you to select under the 'take previous results' drop-down menu? If so, select the time step at 24 hours and that will give you the final conditions from the first study as the initial conditions for the second.
Alternatively, you might try running this as a single study. With your transient option ticked, go into calculation control options>saving>full results. Change the drop down to clock, and select the time steps you wish to have full results for. You could save the results every hour, for example, and plot temperature every hour over 48 hours.
Transient analysis can take a while to solve, so use a very coarse mesh at first to make sure it works alright and does what you want, then refine the mesh later.
Hope this helps