Custom Type Name error

here is structure im playing with

Type Light_Source

Field ID
Field Name$
Field Range#
Field Intensity#
Field Speed#
Field Distance#

End Type

and here is Types sort routine im using, in order to sort all light sources based in Distance#
;-------------------------------------------------------------
Local Item.Light_Source, NextItem.Light_Source, p.Light_Source
Local temp#
NextItem=After After First Item <------ This is line where error is reported, pointed on to NextItem
Repeat
If NextItem = Null Then Return
Item = NextItem : NextItem=After NextItem
temp#=Item\Distance# : p = Before Item
While temp# < p\Distance#
p = Before p
Wend
Insert Item After p
Forever
;-------------------------------------------------------------

All data about Types fields are processed, entered before so its fine, I have checked it..now, when i run program, I got "custom type name name not found" error...what confusing me is when i isolate same routine and data outside of main program and test as separate program, its working...what im doing wrong here??

The After operator refers to a particular object, so

NextItem=After NextItem

is correct usage. The First operator refers to the entire list for a user defined type. You need

NextItem=After After First Light_Source