Look carefully at the TRY block:
Line 1: You set your OleDbCommand (cmd) to be a SELECT statement
Line 2: You set Str to be the UPDATE query.
Line 3: You execute the cmd statement, not the UPDATE stored in Str
Try
cmd = New OleDbCommand("Select * From Usysreportname", cnnOLEDB)
Str = "UPdate() UsysReportName SET ReportName =" & ReportName
cmd.ExecuteNonQuery()
Catch ex As Exception