Yii 1.1.16未定义的偏移误差

Question

I have an app with Yii 1.1.16 framework. When i'm trying it on my web-hosting i got an error 500 (Undefined offset: 3). In application.log

2015/09/28 11:02:43 [error] [php] Undefined offset: 3 (/var/www/clients/client205/web763/web/protected/models/tools/Salary/ToolSalaryForm.php:258)
Stack trace:
#0 /var/www/clients/client205/web763/web/framework/yiilite.php(3652): CInlineAction->runWithParams()
#1 /var/www/clients/client205/web763/web/framework/yiilite.php(3637): ToolSalaryController->runAction()
#2 /var/www/clients/client205/web763/web/framework/yiilite.php(3627): ToolSalaryController->runActionWithFilters()
#3 /var/www/clients/client205/web763/web/protected/controllers/ToolController.php(42): ToolSalaryController->run()
#4 unknown(0): ToolController->actionProcess()
#5 /var/www/clients/client205/web763/web/framework/yiilite.php(4121): ReflectionMethod->invokeArgs()
#6 /var/www/clients/client205/web763/web/framework/yiilite.php(4138): CInlineAction->runWithParamsInternal()
#7 /var/www/clients/client205/web763/web/framework/yiilite.php(3652): CInlineAction->runWithParams()
#8 /var/www/clients/client205/web763/web/framework/yiilite.php(6895): ToolController->runAction()
#9 /var/www/clients/client205/web763/web/framework/yiilite.php(6904): CFilterChain->run()
#10 /var/www/clients/client205/web763/web/framework/yiilite.php(4030): CAccessControlFilter->filter()
#11 /var/www/clients/client205/web763/web/framework/yiilite.php(6937): ToolController->filterAccessControl()
#12 /var/www/clients/client205/web763/web/framework/yiilite.php(6892): CInlineFilter->filter()
#13 /var/www/clients/client205/web763/web/framework/yiilite.php(3642): CFilterChain->run()
#14 /var/www/clients/client205/web763/web/framework/yiilite.php(3627): ToolController->runActionWithFilters()
#15 /var/www/clients/client205/web763/web/framework/yiilite.php(1761): ToolController->run()
#16 /var/www/clients/client205/web763/web/framework/yiilite.php(1681): CWebApplication->runController()
#17 /var/www/clients/client205/web763/web/framework/yiilite.php(1202): CWebApplication->processRequest()
#18 /var/www/clients/client205/web763/web/index.php(25): CWebApplication->run()
REQUEST_URI=/Tool/Salary/index

And ToolSalaryForm.php starting from 251 until 263 lines:

public function validateInstitutionList($attr) {

  if ($this->institutionAll == self::INSTITUTION_CHOOSE) {

    if (!$this->institutions || (count($this->institutions) == 1 && isset($this->institutions['all']))) {

      $this->addError($attr, 'Выберете учреждения');

    }

  }

}

Error log of server is empty. And access log is:

x.x.x.x - - [28/Sep/2015:11:02:43 +0900] "POST /Tool/Salary/index HTTP/1.0" 500 3312 "http://subdomain.domain.ru/Tool/Salary/index" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.99 Safari/537.36"

But when i install Denwer proj on my local PC and trying to run this app - all work perfactly. I didn't write the app, so i can not understand what's going wrong. I hope u can help me and sorry for my english :D