Show Userform - Invalid Property Value Error

I created a form that my employees could use to log their work. When I toggle between the combobox and the qtytextbox I get an "invalid property value" error that debugs to the line of code that opens the userform. I have no idea how to fix this. The spreadsheet has a button that shows the userform. This code is:

Private Sub rectangle1_click()
If frmLCWork.Visible = False Then frmLCWork.Show
Exit Sub
End Sub

The userform has a combobox for employees to select the completed "task", a quantity textbox and then an "add to log" button. The form code is:

Option Explicit
Private Sub cmdAdd_Click()
Dim sStep As String
Dim Row As Long
'check for a task
If Trim(Me.cbxTask.Value) = "" Then
Me.cbxTask.SetFocus
MsgBox "Please specify which task you completed."
Exit Sub
End If....................