Erro while attempting to perform a type cast in derived column component

Hi

I'm trying to perform a DataType change of a column from DataType DT_STR to (DT_UI1).

The syntax i'm using is: (DT_UI1)LEFT(RIGHT(Section,3),1)

I'm getting the following error when i'm executing the package:

I'll be happy for assustance :)

thanks

Yaron

Yaron