Group Table based on a numeric column converted to Text column

[Sudheeshp]

Please help me, in my table Trx ID which is numberic; I have converted into text and when i group basedon this, the error message is as follows:

DataFormat.Error: We couldn't convert to Number.
Details:
Trx ID

Table.Group(#"Removed Columns2", {"Trx ID"}, {{"Sum", each List.Sum([Gross]), type nullable number}})

[ronrsnfld]

Is the Table.Group step the very first step where that error appears?  Or does it appear on preceding steps also? If the latter, where is the first step when that appears?