It is because the system did not aggregate two different quantity units. If you only need the values, use the option "Ignore quantity units differences"
There are the list of standard country groups:
America LAIA 32 +68 +76 +152 +170 +192 +218 +473 +484 +600 +604 +858 +862
APEC 490 +36 +96 +124 +152 +156 +344 +360 +392 +410 +458 +484 +554 +598 +604 +608 +643 +702 +764 +841 +842 +704
ASEAN 096 +116 +360 +418 +458 +104 +608 +702 +704 +764
Asia 4 +51 +490 +879 +31 +48 +50 +64 +96 +116 +156 +344 +196 +626 +866 +868 +886 +720 +268 +699 +356 +360 +364 +368 +376 +392 +400 +398 +408 +410 +414 +417 +418 +422 +446 +458 +462 +496 +104 +524 +536 +275 +512 +586 +588 +459 +608 +634 +647 +461 +457 +682 +698 +702 +144 +760 +762 +764 +792 +795 +784 +860 +704 +887
Asia Former USSR 031 +051 +268 +398 +417 +762 +795 +860
Asia Middle East 879 +48 +196 +886 +720 +364 +368 +400 +414 +422 +536 +275 +512 +634 +682 +760 +792 +784 +887
CARICOM 028 +052 +084 +212 +308 +328 +388 +500 +658 +659 +662 +670 +740 +780
CIS 051 +031 +112 +268 +398 +417 +498 +643 +762 +795 +804 +860
COMESA 24 +108 +174 +180 +262 +818 +232 +231 +404 +450 +454 +480 +516 +646 +690 +736 +748 +834 +800 +894 +716
ECOWAS 204 +854 +132 +384 +270 +288 +324 +624 +430 +466 +562 +566 +686 +694 +768
Europe 8 +20 +40 +112 +56 +58 +70 +100 +191 +203 +200 +208 +233 +221 +697 +568 +492 +234 +246 +278 +280 +890 +251 +276 +292 +300 +348 +352 +372 +381 +428 +440 +442 +470 +528 +579 +616 +620 +498 +642 +643 +703 +705 +724 +752 +757 +807 +826 +804 +891
Europe East 008 +100 +200 +203 +221 +278 +348 +616 +642 +703
Europe EFTA 352 +579 +697 +757
Europe Former USSR 112 +233 +428 +440 +498 +643 +804
European Union 15 040 +056 +058 +208 +246 +251 +276 +280 +300 +372 +381 +442 +492 +528 +620 +724 +752 +826
Least Developed Countries 4 +24 +50 +204 +64 +854 +108 +116 +132 +140 +148 +174 +180 +262 +226 +232 +231 +270 +324 +624 +332 +296 +418 +426 +430 +450 +454 +462 +466 +478 +508 +104 +524 +562 +646 +882 +678 +694 +90 +706 +736 +834 +768 +798 +800 +548 +887 +894
Mercosur 032 +076 +600 +858
Mercosur plus Chile 032 +076 +152 +600 +858
Miscellaneous 837 +838 +839 +899
NAFTA 124 +484 +841 +842
North Africa 012 +290 +434 +504 +732 +736 +788 +818
North America 060 +124 +304 +666 +841 +842
Oceania 36 +162 +166 +184 +242 +582 +258 +296 +584 +583 +580 +520 +540 +554 +570 +574 +527 +585 +598 +612 +882 +90 +772 +776 +798 +849 +548 +876
OECD 36 +40 +56 +58 +124 +203 +208 +492 +246 +280 +251 +276 +300 +348 +352 +372 +381 +392 +442 +484 +528 +554 +579 +616 +620 +410 +703 +724 +752 +757 +792 +842 +841 +826
OPEC 012 +360 +364 +368 +414 +434 +566 +634 +682 +784 +862
Other America CACM 188 +222 +320 +340 +471 +558
Other America Caribbean 660 +28 +533 +44 +52 +92 +129 +136 +192 +212 +214 +308 +312 +332 +388 +474 +500 +532 +530 +659 +658 +662 +670 +780 +796 +850
SACU 072 +426 +516 +710 +711 +748
World (Aggregate) all