主题：字符转数值，再转字符 ，帮我看看，这代码错在哪里？

Dim mx11 As WinForm.TextBox = e.Form.Controls("TBMX01")
Dim mx12 As WinForm.TextBox = e.Form.Controls("TBMX02")
Dim mx16 As WinForm.TextBox = e.Form.Controls("TBMX06")
Dim Multi As String = mx11.text
Dim pars() As String = Multi.Split("-")
Dim e1 As Double = Val(pars(0))
Dim e2 As Double = Val(pars(1))
Dim Multi1 As String = mx12.text
Dim pars1() As String = Multi1.Split("-")
Dim c1 As Double = Val(pars1(0))
Dim c2 As Double = Val(pars1(1))
Dim z1 As Double
Dim z2 As Double
z1 = e1 + c1
z2 = e2 + c2
Dim y As String
Dim y1 As String
y = z1
y1 = z2
mx16.text = y + "-" + y1

 字符转数值，再转字符 ，帮我看看，这代码错在哪里？

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