Unsuported Column Type

Hello,

I have 2 Excel files. I use “concatenate” to obtain a single file. Then I use Excel Writer and I get this message “Execute failed: Unsupported column type ‘?’. Please remove corresponding column(s) from the input table.”

I don’t have a column type “?” only “String”, “Number Integer” “Number Double”

If I use Excel Writer for each file individually, it works. Where could this problem come from?

Thanks

Br