Convert DT_WSTR to DT_Datetimestamp

Hi I have vb6 code ("VALID_DATE") = FormatDate(Mid(Table_Fields(1), 85, 8)),for which i have converted it to SUBSTRING(Data_table,95,8)...

I want to convert SUBSTRING(Data_table,95,8) to (DT_DBTIMESTAMP) in derived column because my destination table has (DT_DBTIMESTAMP) as datatype.

Please suggest a solution..

Thanks in advance..