Green Arrow after converting from CSV to Excel

Hi, 

i'd the need to convert a CSV file to XLS file, so far no problem, searching around I've found a few solutions and merged them in one suitable, for me, solution. The problem is that when i open the excel file (xls) all green arrows appear next to the value that do resemble dates and  number if it is not the case. If there a way to suppress this warning ?

i've tried these options :

$excelApp.ErrorCheckingOptions.BackgroundChecking = $True
$excelApp.ErrorCheckingOptions.NumberAsText = $False
$excelApp.ErrorCheckingOptions.TextDate = $False
$excelApp.ErrorCheckingOptions.EvaluateToError = $False
$excelApp.ErrorCheckingOptions.InconsistentFormula = $False

but the green arrow is still there.

Any help would be appreciated.

Regards