Changing columns types except selected ones

[Chrisjr]

Hello All, 

I have the following table: 

Brand	Category	March	April	May
AB	DOP	500	750	807
AC	PDO	200	850	890
AD	OOB	150	970	750
AA	DOP	680	160	690

I am trying to create a function that would change the column types of all columns expceted the columns Brand and Category. 

(The other column's names will always change. The column "Brand" and "Category" will always be the 2 first columns and their names will never change)

I have tried the following function but doesn't work: 
        = Table.TransformColumnTypes(#"End stage 3",
List.Transform(
List.RemoveFirstN(
Table.ColumnNames(Source),
2
),
each {_, Int64.Type}
))

I get an error message : "Expression.Error: The column 'Item' of the table wasn't found.
Details:
Item"

but nowhere in my table or transformations I have a column names Item. 

Anyone has an idea how I could achieve this? 

[Chrisjr]

Super, many thanks @wdx223_Daniel .

What was my mistake? 

[Chrisjr]

I see you replaced the source with the previous step. 

[wdx223_Daniel · Accepted solution]

= Table.TransformColumnTypes(#"End stage 3",
List.Transform(
List.RemoveFirstN(
Table.ColumnNames(#"End stage 3"),
2
),
each {_, Int64.Type}
))