TSTest.LastRun() method seems to always return null

I have a method that is looping through previously passed tests in a test set and retreiving the last run information and placing that information into an array. I keep having the issue when I am setting my Run object to the TSTest.LastRun object. I keep getting a not set to an instance of an object error. Cant find the issue. I have verified that there are runs on that certain TSTest object. Code...

    Public Shared Function retrievePreviousResults(hpqc As TDConnection, listOfPassedTests As ArrayList) As ArrayList

        Dim stepFactory As StepFactory        

        Dim runStepsList As List        

        Dim designDelimeter As String = ":::"        

        Dim previousTestsArrayList As New ArrayList

        For Each tsTest As TSTest In listOfPassedTests

            Dim testID As String = tsTest.TestId            

            Dim testName As String = tsTest.Name

            Dim run As Run = tsTest.LastRun                      'ISSUE IS HERE. Run object always is null after this statement'

            stepFactory = run.StepFactory            

            runStepsList = stepFactory.NewList("")            

            Dim totalSteps As Integer = runStepsList.Count

            Dim acutalLastStep As [Step] = runStepsList.Item(totalSteps)            

            Dim actualLastRunStep As String = acutalLastStep.Field("ST_ACTUAL")

            Dim stringBuilder As New System.Text.StringBuilder

            stringBuilder.Append(testID)            

            stringBuilder.Append(designDelimeter)            
            stringBuilder.Append(testName)            

            stringBuilder.Append(designDelimeter)            

            stringBuilder.Append(actualLastRunStep)

            Dim finalStepInformation As String = stringBuilder.ToString()

            previousTestsArrayList.Add(finalStepInformation)

        Next

        Return previousTestsArrayList

    End Function