How do you check if a layer in TOC is a vector or a raster/image? vb.net

I am writing code for a button in a windows.form to export to KMZ any selected features from any vector layer in a maps TOC.
Code works well with vector layers but seems to crash if there is any imagery or raster in the TOC.
I understand that Ifeaturelayer is for vector geometries only, so I am guessing I need to include a check if the current layer is a vector, if so continue with code, otherwise skip the code. But being very new to arcobjects, I cant figure out how to do this?

See below:

Public Sub ExportSelectedFeaturesToKML()

Dim pMxDoc As IMxDocument
Dim pMap As IMap
Dim pFeatureLayer As IFeatureLayer
Dim LayerName As String


pMxDoc = My.ArcMap.Document
pMap = pMxDoc.FocusMap

'Counts number of Layers in TOC

Dim LayerCount As Integer
LayerCount = pMap.LayerCount


'******** Loops through layers in TOC and checks if there are any selected features, if so exports them as KMZ.


For i = 0 To LayerCount - 1

pFeatureLayer = pMap.Layer(i)

'Determines the Name of current Layer for KMZ file name
LayerName = pMap.Layer(i).Name


'Calculates current date and time and provides as a string
Dim rightNow As DateTime = DateTime.Now
Dim strCurrentDateTimeString As String
strCurrentDateTimeString = rightNow.ToString("ddd_dd_MMM_yyyy_hh_mm_ss_tt")

'Checks if layer has any selected features
Dim pLayer As ILayer
pLayer = pMap.Layer(i)

Dim pFeatureSelection As IFeatureSelection
pFeatureSelection = pLayer

Dim PSelectionSet As ISelectionSet2
PSelectionSet = pFeatureSelection.SelectionSet

Dim SelectionCount As Integer
SelectionCount = PSelectionSet.Count

If SelectionCount > 0 Then

' Initialize the geoprocessor.
Dim GP As Geoprocessor = New Geoprocessor()

Dim LayerToKMLTool As ESRI.ArcGIS.ConversionTools.LayerToKML = New ESRI.ArcGIS.ConversionTools.LayerToKML()
GP.SetEnvironmentValue("workspace", "C:\Data")
LayerToKMLTool.layer = pFeatureLayer
LayerToKMLTool.layer_output_scale = 1
LayerToKMLTool.out_kmz_file = LayerName & "_" & strCurrentDateTimeString & ".kmz"

GP.Execute(LayerToKMLTool, Nothing)
End If

Next


End Sub


Any suggestions would be greatly appreciated.
Justin