=IF(ISNUMBER(SEARCH(H3,Sheet1!B:B,0)),INDEX(Sheet1!E:E,SEARCH(H3,Sheet1!B:B,0)),H3)

I have two sheets in my workbook. One sheet has the names as a column with first name and a column with last name. My other sheet has a column with first middle and last name.

I want to search the last name and if you find it return whatever is in column E.

Column H is first middle and last
Sheet1 Column B is last name. And, Sheet1 Column E is the department.

What is wrong with my formula above.