Earlier working nested if statement formula no longer working in Google New Sheet

There is a formula (for converting amount in digits into amount in words) which was working fine in the earlier version of Google sheet. In new sheet, it is no longer working and giving the following error :

Error : Function CHOOSE parameter 1 value is 0. Valid values are between 1 and 19 inclusive.

The formula is a little bigger and complex (multiple if function) - please see the link below the see the formula - (in Cell B2) -

http://ift.tt/2nU2QrV

Thank you!