Why some Singapore best swimmesr NOT in YOG

[peterpan707]

1. KHOO Chien Yin Lionel -
50m Breaststroke (U17 Boy) - 0:29.29 (9 Jun 2010)
100m Breaststroke (U17 Boy) - 1:04.39 (19 Mar 2010)
200m Breaststroke (U17 -Boy) - 2:20.52 (13 Jun 2010)

http://www.swimming.org.sg/swmrecords_BoysUnder17.html

YOG :
50m Breaststroke PANG Sheng Jun 30.11
100m Breaststroke PANG Sheng Jun 1:06.46

2. DZULHAILI bin Mohd Kamal
50m Butterfly (U17 Boy) 0:25.57 11 Jun 2010
http://www.swimming.org.sg/swmrecords_BoysUnder17.html

YOG :
50m Butterfly PANG Sheng Jun 25.63

3. QUAH Ting Wen
100m Freestyle (U17 Girl) 0:55.57 06 Jul 2009
200m Freestyle (U17 Girl) 1:59.21 03 Jul 2009


http://www.swimming.org.sg/swmrecords_GirlsUnder17.html

YOG :

100m Freestyle WINATA Adeline Shu Jian 1:00.64
200m Freestyle WINATA Adeline Shu Jian 2:12.69

4. LIM Jia Yi Shana
50m Backstroke (U17 Girl) 0:28.58 18 Mar 2010
100m Backstroke (U17 Girl) 1:03.25 01 Aug 2009

http://www.swimming.org.sg/swmrecords_GirlsUnder17.html

YOG :
50m Backstroke WINATA Adeline Shu Jian 31.48
100m Backstroke KOH Chriselle Wyn Jia 1:09.93
100m Backstroke WINATA Adeline Shu Jian 1:08.06

5. HO Ru'En Roanne
50m Breaststroke (U17 Girl) 0:32.44 03 Jul 2009

http://www.swimming.org.sg/swmrecords_GirlsUnder17.html

YOG :
50m Breaststroke LIM Xin Jing Cheryl 33.65


Why are these top swimmer not given the chance to take part in YOG or they simply they are also not interested?