vb问题（s021）北京2008。。怎样取括号内的字符串

Private Sub Command1_Click()
Dim St As String, Stb As String
St = "（s021）北京2008"
Stb = Mid(St, 2, 4)
Print St
Print Stb

End Sub

Private Sub Command1_Click()
Dim St As String, Stb As String ,iB,iE
St = "(s021)北京2008"
For i = 1 to Len(St)
If Mid$(St, i,1) = "(" Then iB=i
If Mid$(St, i,1) = ")" Then iE=i:Exit For
Next
Stb = Mid(St, iB+1, iE-iB-1)
Print St
Print Stb
End Sub