How do I get sum product to ignore empty cells to calculate the cost basis of shares?

[ExcelAdv]

Which formula of sum product should I put in the column C cells to calculate the cost basis of shares, which ignores the empty cells in column B and so considers only the prices in column A by which the quantity in column B is entered?
I tried to use the following formula, but it gives me the wrong result 1 instead of the right result 1,2712:
=SUMMENPRODUKT((A$2:A$30)*(B$2:B$30<>""))/SUMMEWENN(B2:B30;">0";A2:A30)

Whit the desired formula:
If I enter the first quantity 1 in cell B1, should appear the cost basis 1,2725 in cell C2
If I enter the second quantity 3 in cell B8, should appear the cost basis 1,2721 in cell C8
If I enter the third quantity 4 in cell B17, should appear the cost basis 1,2712 in cell C17

Mappe1 (version 2).xlsb
	A	B	C	D	E	F
1	Price	Number of Long Contracts	Cost Basis
2	1,2725	1	1,2725
3	1,2724
4	1,2723
5	1,2722
6	1,2721
7	1,2720
8	1,2719	3	1,2721
9	1,2718
10	1,2717
11	1,2716
12	1,2715
13	1,2714
14	1,2713
15	1,2712
16	1,2711
17	1,2710	4	1,000000		1,2712	(right answer)
18	1,2709
19	1,2708
20	1,2707
21	1,2706
22	1,2705
23	1,2704
24	1,2703
25	1,2702
26	1,2701
27	1,2700
Tabelle1

Cell Formulas
Range	Formula
C2	C2	=A2*B2
C17	C17	=SUMPRODUCT((A$2:A$30)*(B$2:B$30<>""))/SUMIF(B2:B30,">0",A2:A30)
A3:A27	A3	=A2-0.0001

 

[ExcelAdv]

Excuse me. This was the mini sheet I wanted to upload. Please disregard the previous:

Mappe1 (version 2).xlsb
	A	B	C	D	E	F
1	Price	Number of Long Contracts	Cost Basis
2	1,2725	1	1,2725
3	1,2724
4	1,2723
5	1,2722
6	1,2721
7	1,2720
8	1,2719	3	1,2721
9	1,2718
10	1,2717
11	1,2716
12	1,2715
13	1,2714
14	1,2713
15	1,2712
16	1,2711
17	1,2710
18	1,2709
19	1,2708
20	1,2707
21	1,2706
22	1,2705
23	1,2704
24	1,2703
25	1,2702
26	1,2701
27	1,2700	4	1		1,2712	(right answer)
28	1,2699
29	1,2698
30	1,2697
31	1,2696
32	1,2695
Tabelle1

Cell Formulas
Range	Formula
C2	C2	=A2*B2
C27	C27	=SUMPRODUCT(($A$2:A27)*(B$2:B27<>""))/SUMIF($B$2:B27,">0",$A$2:A27)
A3:A32	A3	=A2-0.0001

 

[ExcelAdv]

In the meanwhile I solved it with a column to be hidden. If you have a more elegant solution with only a formula in column C, I would appreciate it.

Cost Basis for Scaling In.xlsx
	A	B	C	D	E
1	Price	Number of Long Contracts	Cost Basis		Column to be hidden
2	1,2725	1	1,2725		1,2725
3	1,2724				0
4	1,2723				0
5	1,2722				0
6	1,2721				0
7	1,2720				0
8	1,2719	3	1,2721		3,8157
9	1,2718				0
10	1,2717				0
11	1,2716				0
12	1,2715				0
13	1,2714				0
14	1,2713				0
15	1,2712				0
16	1,2711				0
17	1,2710				0
18	1,2709				0
19	1,2708				0
20	1,2707				0
21	1,2706				0
22	1,2705				0
23	1,2704				0
24	1,2703				0
25	1,2702				0
26	1,2701				0
27	1,2700	4	1,2710		5,08
28	1,2699				0
29	1,2698				0
30	1,2697				0
31	1,2696				0
32	1,2695				0
Tabelle1

Cell Formulas
Range	Formula
C32,C27,C7:C25,C2:C3	C2	=(IF(B2<>"",ROUND(SUM($E$2:E2)/(SUM($B$2:B2)),4),""))
A3:A32	A3	=A2-0.0001
E2:E32	E2	=A2*B2

 

[Peter_SSs]

Is it something like this that you are after?
If not, please details how you cam up with 1.2712 as the "right answer" for row 27

24 01 05.xlsm
	A	B	C
1	Price	Number of Long Contracts	Cost Basis
2	1.2725	1	1.2725
3	1.2724
4	1.2723
5	1.2722
6	1.2721
7	1.272
8	1.2719	3	1.2721
9	1.2718
10	1.2717
11	1.2716
12	1.2715
13	1.2714
14	1.2713
15	1.2712
16	1.2711
17	1.271
18	1.2709
19	1.2708
20	1.2707
21	1.2706
22	1.2705
23	1.2704
24	1.2703
25	1.2702
26	1.2701
27	1.27	4	1.2710
28	1.2699
29	1.2698
30	1.2697
31	1.2696
32	1.2695
Cost

Cell Formulas
Range	Formula
A3:A32	A3	=A2-0.0001
C2:C32	C2	=IF(B2="","",SUMPRODUCT(A$2:A2,B$2:B2)/SUM(B$2:B2))

 

[ExcelAdv]

Is it something like this that you are after?
If not, please details how you cam up with 1.2712 as the "right answer" for row 27

24 01 05.xlsm
	A	B	C
1	Price	Number of Long Contracts	Cost Basis
2	1.2725	1	1.2725
3	1.2724
4	1.2723
5	1.2722
6	1.2721
7	1.272
8	1.2719	3	1.2721
9	1.2718
10	1.2717
11	1.2716
12	1.2715
13	1.2714
14	1.2713
15	1.2712
16	1.2711
17	1.271
18	1.2709
19	1.2708
20	1.2707
21	1.2706
22	1.2705
23	1.2704
24	1.2703
25	1.2702
26	1.2701
27	1.27	4	1.2710
28	1.2699
29	1.2698
30	1.2697
31	1.2696
32	1.2695
Cost

Cell Formulas
Range	Formula
A3:A32	A3	=A2-0.0001
C2:C32	C2	=IF(B2="","",SUMPRODUCT(A$2:A2,B$2:B2)/SUM(B$2:B2))

Waw, Peter_SSs, exactly what I needed and very elegant and simple formula.
I don't know why was 1.2712 considered the "right" answer, maybe the author considered some slippage or something else.
Anyway your solution is great. Many thanks

 

[Peter_SSs]

You're welcome. Thanks for the follow-up.