run time error adding values to worksheet

I'm trying to write code that finds the row value of a cell with a certain value from a combobox1 and then insert other data into the columns next to it. I have this code so far and it comes up with an error saying 'run time error 13- type mismatch) I've put an arrow next to where it highlights this error..

Private Sub BookButton_Click()
Dim c As Variant

Dim datev As String

Dim r As Variant
datev = ComboBox1.value
c = Application.Match(datev, Worksheets("Calender").Range("A:A"), 0)
     With Worksheets("Calender").Range("A:A")
 
  .Offset(c, 3).value = HostsName.value
   End With
End Sub