Error when importing deals

Error when importing deals

Hi,
am new to Zoho and in the middle of trying it out.
I am trying to import deals from a xlsx file (tried csv as well with same results) and everything works fine except for the Amount field. For no reason that I can understand in some rows the Amount field is not populated even if the value is there in the xlsx file. 
In fact, out of 400 rows only a few dozen import correctly while in the rest it is blank.

what am I doing wrong?

I checked for weird characters and all seems to be ok.
I tried to import xlsx, xls and csv with the same result.
I tried changing the cell type in excel to number instead of currency, same result.
I removed decimals and thousand separators, same result.

Not sure where the problem is if on the source file or the import process...

any help would be great since I am evaluating the product and this is an issue for further testing!!

thanks