The {particles} of 'all' must be <element>. So <sequence> is prohibited.
http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/#Model_Groups
TEST particles00103m1 - <sequence> as one of {particles} (invalid schema)
| Item | Value | 
|---|---|
| title | particles00103m1 - <sequence> as one of {particles} (invalid schema) | 
| name | particles00103m1 | 
| source | ../particles00103m1.xsd | 
| schemaName | ../particles00103m1.xsd | 
| keywords | schema negative | 
| package | javasoft.sqe.tests.mgroup.particles.particles00103m.particles00103m1 |