The parameters for RAT are backwards. It should be:

lnLastStringPosition = RAT("CHANGE ORDER", lcComments)

>I am trying to get the numeric position of a string inside a string. The string looks like this:
>
>"CHANGE ORDER 01CHANGE ORDER 02CHANGE ORDER03"
>
>The string to search is "CHANGE ORDER". I want to get the right most string position, which in this case should be 31, but it comes up as zero (0) when I use the following code:
>
>

lcComments = "CHANGE ORDER 01CHANGE ORDER 02CHANGE ORDER03"

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>

lnLastStringPosition=RAT(lcComments,"CHANGE ORDER")

>
>

?lnLastStringPosition

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>Why this comes out as a value of 0, I do not understand.
>
>Perhaps my 10-mile hike with my son and his SCOUT Troop this past weekend in Joshua Tree, California, has affected my mental skills.