Why Do WTO Complaints Fail?

As we all know, most WTO complaints are successful.  I've got the figures at about 90% for cases in which at least one violation is found.

So what happens in those cases where the complaint did not succeed?  What are the various reasons that complaints fail?

I can't recall anyone looking into this, and I thought it was a worthy topic, so here are all the losing cases -- just regular disputes, not Article 21.5s -- in case anyone wants to analyze them:

Dispute Title DS Number Adoption Date Violation?
Total Records: 15        
Brazil - Coconut Brazil - Measures Affecting Desiccated Coconut 22 Mar 20, 1997 No
Japan - Film Japan - Measures Affecting Consumer Photographic Film and Paper 44 Apr 22, 1998 No
EC - Computer Equipment European Communities - Customs Classification of Certain Computer Equipment 62 Jun 22, 1998 No
Guatemala - Cement I Guatemala - Anti-Dumping Investigation Regarding Portland Cement from Mexico 60 Nov 25, 1998 No
U.S. - Section 301 United States - Sections 301-310 of the Trade Act of 1974 152 Jan 27, 2000 No
Korea - Government Procurement Korea - Measures Affecting Government Procurement 163 Jun 19, 2000 No
EC - Asbestos European Communities - Measures Affecting Asbestos and Asbestos-Containing Products 135 Apr 05, 2001 No
U.S. - Export Restraints United States - Measures Treating Export Restraints as Subsidies 194 Aug 23, 2001 No
U.S. - Section 129 United States - Section 129(c)(1) of the Uruguay Round Agreements Act 221 Aug 30, 2002 No
U.S. - Textiles Rules of Origin United States - Rules of Origin for Textiles and Apparel Products 243 Jul 21, 2003 No
U.S. - Corrosion-Resistant Steel Sunset Review United States - Sunset Review of Anti-Dumping Duties on Corrosion-Resistant Carbon Steel Flat Products from Japan 244 Jan 09, 2004 No
Canada - Hormones Suspension Canada - Continued Suspension of Obligations in the EC - Hormones Dispute 321 Nov 10, 2008 No
U.S. - Hormones Suspension United States - Continued Suspension of Obligations in the EC - Hormones Dispute 320 Nov 10, 2008 No
India - Additional Duties India - Additional and Extra-Additional Duties on Imports from the United States 360 Nov 17, 2008 No
U.S. - Tyres United States - Measures Affecting Imports of Certain Passenger Vehicle and Light Truck Tyres from China 399 Oct 05, 2011 No