Storing Values In Other Fields

[srm]

I'm creating a custom field in which I want to combine multiple values
into one. I've use the combination field but cannot get the combined
values to appear in the third field. I have one field using date and
the other using time. In the third field I'm then combining them but I
always get an error or no values.

I'm sure there is something simple I'm missing. Any help would be
appreciated.

Shawn