some one please help me regarding why the index error is occuring...
i find the application works fine for a few values of textidx but only for a few distinct values this error occurs....

kindly help me

Traceback (innermost last):

Module ZPublisher.Publish, line 119, in publish
Module ZPublisher.mapply, line 88, in mapply
Module ZPublisher.Publish, line 42, in call_object
Module Shared.DC.Scripts.Bindings, line 313, in __call__
Module Shared.DC.Scripts.Bindings, line 350, in _bindAndExec
Module Products.PageTemplates.ZopePageTemplate, line 330, in _exec
Module Products.PageTemplates.ZopePageTemplate, line 426, in pt_render
Module Products.PageTemplates.PageTemplate, line 89, in pt_render
Module zope.pagetemplate.pagetemplate, line 117, in pt_render
Module zope.tal.talinterpreter, line 271, in __call__
Module zope.tal.talinterpreter, line 346, in interpret
Module zope.tal.talinterpreter, line 824, in do_loop_tal
Module zope.tal.talinterpreter, line 346, in interpret
Module zope.tal.talinterpreter, line 536, in do_optTag_tal
Module zope.tal.talinterpreter, line 521, in do_optTag
Module zope.tal.talinterpreter, line 516, in no_tag
Module zope.tal.talinterpreter, line 346, in interpret
Module zope.tal.talinterpreter, line 590, in do_setGlobal_tal

Module zope.tales.tales, line 696, in evaluate
URL: /news/SearchReport
Line 79, Column 2
Expression: <PythonExpr container.data.restrictedTraverse(storynb[0]).getChapterInfo(storynb[1], kfMax)>
Names:

{'container': <Folder at /news>,
 'context': <Folder at /news>,
 'default': <object object at 0xb7d62528>,
 'here': <Folder at /news>,

 'loop': {u'result': <Products.PageTemplates.Expressions.PathIterator object at 0x1993cfcc>},
 'nothing': None,
 'options': {'args': ()},
 'repeat': <Products.PageTemplates.Expressions.SafeMapping object at 0x186ab80c>,

 'request': <HTTPRequest, URL=http://kmi-vid01.open.ac.uk:8080/news/SearchReport>,
 'root': <Application at >,
 'template': <ZopePageTemplate at /news/SearchReport>,

 'traverse_subpath': [],
 'user': <User 'mmis'>}

Module Products.PageTemplates.ZRPythonExpr, line 49, in __call__
__traceback_info__: container.data.restrictedTraverse(storynb[0]).getChapterInfo(storynb[1], kfMax)
Module PythonExpr, line 1, in <expression>
Module Shared.DC.Scripts.Bindings, line 313, in __call__
Module Shared.DC.Scripts.Bindings, line 350, in _bindAndExec
Module Products.PythonScripts.PythonScript, line 327, in _exec
Module None, line 26, in getChapterInfo
<PythonScript at /news/getChapterInfo used for /news/data/20071124>
Line 26
Module AccessControl.ZopeGuards, line 67, in guarded_getitem

IndexError: list index out of range