>You are not looking at the values I think. FieldValue is a date() value. Look at the vars and the code in one of the CASE conditions.
OK, you want from date to get string:

*** 20081231 or CCYYMMDD
FieldValue = DATE(2008,12,31)
NewFieldValue = DTOS(FieldValue)

*** 12312008 or MMDDCCYY
FieldValue = DATE(2008,12,31)
NewFieldValue = SUBSTR(DTOS(FieldValue),5,2)+RIGHT(DTOS(FieldValue),2)+LEFT(DTOS(FieldValue),4)

*** 31122008 or DDMMCCYY
FieldValue = DATE(2008,12,31)
NewFieldValue = RIGHT(DTOS(FieldValue),2)+SUBSTR(DTOS(FieldValue),5,2)+LEFT(DTOS(FieldValue),4)

>>>>>>>DO CASE
>>>>>>> CASE FormatFieldValue = 'CCYYMMDD' && Should be "20080101"
>>>>>>> NewFieldValue = EVALUATE("ALLTRIM(TRANSFORM(DTOS(FieldValue), '@R " + REPLICATE('!',FieldLength) + "'))")
>>>>>>> CASE FormatFieldValue = 'MMDDCCYY' && Should be "01012008"
>>>>>>> NewFieldValue = EVALUATE("ALLTRIM(TRANSFORM(DTOS(FieldValue), '@R " + REPLICATE('!',FieldLength) + "'))")
>>>>>>> OTHERWISE && Leave it alone other than converting to text
>>>>>>> NewFieldValue = EVALUATE("ALLTRIM(TRANSFORM(DTOS(FieldValue), '@R " + REPLICATE('!',FieldLength) + "'))")
>>>>>>>ENDCASE
>>>>>>>