Looping script to set field based on criteria

I'm trying to write a script that will set a field across a found set based on user input and have it looped according to another field's criteria. This is a horrible explanation so here is the situation.

I'm tracking three separate fields. Field A is unique. Field B is dependent on what Field C is and is user inputted. I have a script where I ask given Field C, "what is field B?". It will go ahead and set Field B for all the same Field C, then move to the next Field C that is different. I can get it to loop once, but then it stops looping for the next set. I cannot use a calculation because dependent on the situation, Field B might be 1 of 3 different values, hence being user inputted.

Here is what I have so far.

Sort Records

GoTo first record

Set Variable[$temp]

Loop

If [$temp <> FieldC]

Show Custom Dialog (input field 1 is FieldC, input field 2 is FieldB)

Set Variable[$temp Value:FieldB]

Else

Set Field[FieldB]

End If

Goto Record [next; exit after last]

End Loop

This seems to work with 2 different FieldC but does the third Field C individually and not looped.

Any help would be appreciated.

Thanks.

Hoon