Which function to sum based on criteria

Hello,

I have a table with 2 Sheets.

In Sheet1 I have following:
WEEK DATA ID-NO. PCS. (NO.)
2 05.01.15 AA 20
2 05.01.15 AB 23
TOTAL PCS WK2 = 43
3 12.01.15 AA 30
3 12.01.15 AC 31
TOTAL PCS WK3 = 30
4 17.01.15 AA 20
TOTAL PCS WK4 = 20

In Sheet2 I want to SUM for example all PCS NO. for ID-NO. A.
ID NO. SUM PCS. (NO)
AA =...
AB =...

All data from Sheet1.

How can I do this? I tried with VLOOKUP but nothing, also with MATCH, INDEX, SUMPRODUCT...

Please help me! Thank you!

I would use a pivot table. That is the simplest solution.
See attached.