Dear power users, could someone be so kind to help me out with this file and give me some explanation on what I did wrong?

QuestionMaplePrimes.mw Thank you for you time and help

I am still learning Maple and so I would like to rely on you power users to help me out. I probably doing something which is not allowed or not using the best method. I would appreciate any advice. Thank you in advance    ProcQuestion.mw 

Fitting procedures in Maple are self explaning and easy to perform. However, I was wondering if it is possible to fit data vectors with units. For example one vector would have units of seconds and the other units of length. Thank you for your help.

Perhaps a silly question but is it possible to stack two dataframe columns? When I use the Vector command the columns are stacked but nested.

Thank you for your help

I know you can filter a dataframe by putting constraints on the numeric columns. However, I would like to sort and filter based upon a given string in a column, is this possible? I cannot immediately find this in the help files. Thank you for your assistance.QuestionDataFrame.mw