unable to run python code on a combined table to export the table to a csv

I have created a table which is built by apending multiple tables. But when I try to add a python script to apend this table to a csv everytime there is a refresh , I get an error 

Formula.Firewall: Query 'Summary' (step 'Added Conditional Column') references other queries or steps, so it may not directly access a data source. Please rebuild this data combination.

in the advanced editor here is what my code looks like , cant work out what I am doing wrong

let
Source = Table.Combine({#"Futures_0-2_days", #"Futures_0-5_days", #"Futures_6-14_days", #"Futures_15-31_days", #"Futures 30 days preceeded by N3", #"Futures 30 days preceeded by O3"}),
#"Run Python script" = Python.Execute("d = pandas.DataFrame(dataset)#(lf) #(lf)d.to_csv('C:\QC Checker\QC Checker Metrics.csv, index=False)#(lf)",[dataset=Source]),
in
#"Run Python script"