Get cell value of formula evaluation

How can i get the formula Evaluation value?

If i ask for  DM.FlexCelImport1.CellValue[8,3] the value is #NULL!
if i ask for DM.FlexCelImport1.CellFormula[8,3] the value is ='Sheet1'!C8
if i ask for DM.FlexCelImport1.Cell[8,3].IsFormula the result is true.
I need to khow the value of the formula evaluation.
how can i get it,

CellValue returns the result, but this only works in files that have been recalculated. Sadly FlexCel VCL doesn't calculate formulas, so if you change any value in the sheet, formula results will show as null (until you open them in Excel and it calculates them).

Thank you.

Reopening the the file with excel recalculate the formulas.
That solved my problem.