SSIS Derived Column

Experts:
I have a DTS package that I’m trying to rewrite in SSIS, In my DTS package on one of my transformation were I’m mapping source to destination I have a field that gets populated by a global variable, I use a simple active x script to determine witch variable to use, the script looks like this

Function Main()

If DTSGlobalVariables("i_Max_Skl_Stat_Datetime").Value < DTSGlobalVariables("i_Max_Agt_Stat_Datetime").Value Then

DTSDestination("Data_Datetime") = DTSGlobalVariables("i_Max_Skl_Stat_Datetime").Value

Else

DTSDestination("Data_Datetime") = DTSGlobalVariables("i_Max_Agt_Stat_Datetime").Value

End if
Main = DTSTransformStat_OK
End Function

In SSIS I’m trying to use a Derived Column transformation to accomplish since it has an expression editor but can't see how to use the IF / ELSE logic doesn’t seem to like it, is this not the right transformation to use for this?

Thanks in advance.