Compare Combobox value VB.NET

Question

I have 3 Combobox called: NB1,NB2,NB3. this Comboboxs has 2 values: " - " or another text

If the text of each of these combo boxes is equal to each other, it will give an error (msgbox) and the combo box that has " - " will not be compared. Example:

Combo1	Combo2	Combo3	Result
A	B	A	Error
A	A	A	Error
A	-	A	Error
-	C	A	OK
D	B	A	OK
-	-	-	OK
-	F	A	OK
-	D	D	Error

Thanks for helping me.

Answer 1

i solved this problem by AndAlso Structure. " - " will appear when the value of textbox be 0.

(cb_1.Text = cb_2.Text AndAlso Val(txt_1.Text) > 0)

works fine.