Select - Dropdown Again

Hell Telerik,
i am still facing problems with the select-Control. 
I recorded on a Select-Control the following Select: .SelectByValue("30", true) .
When running the test the first time (in Telerik Test Studio), the select is executed correctly. When rerunning the test, very often it fails here with this error log:
(It fails on the recorded step and in a coded step.)

Do you have any suggestions how i can solve it?
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System.TimeoutException: Wait for condition has timed out
   at ArtOfTest.Common.WaitSync.CheckResult(WaitSync wait, String extraExceptionInfo, Object target)
   at ArtOfTest.Common.WaitSync.For[T](Predicate`1 predicate, T target, Boolean invertCondition, Int32 timeout, WaitResultType errorResultType)
   at ArtOfTest.Common.WaitSync.For[T](Predicate`1 predicate, T target, Boolean invertCondition, Int32 timeout)
   at ArtOfTest.WebAii.Core.Browser.WaitUntilReady()
   at ArtOfTest.WebAii.Core.Browser.ExecuteCommand(BrowserCommand request, Boolean performDomRefresh, Boolean waitUntilReady)
   at ArtOfTest.WebAii.Core.Browser.ExecuteCommand(BrowserCommand request)
   at ArtOfTest.WebAii.Core.Actions.DoSelectDropDown(Element targetElement, String data)
   at ArtOfTest.WebAii.Core.Actions.SelectDropDown(Element targetElement, String text, Boolean useValue)
   at ArtOfTest.WebAii.Design.IntrinsicTranslators.Descriptors.SelectDropDownActionDescriptor.Execute(Browser browser)
   at ArtOfTest.WebAii.Design.Extensibility.HtmlActionDescriptor.Execute(IAutomationHost autoHost)
   at ArtOfTest.WebAii.Design.Execution.ExecutionEngine.ExecuteStep(Int32 order)