Multiple If Statements for a command button?

So I have 4 text boxes within a userform and the user MUST enter something in each text box. How do I code a data validation so that all 4 textboxes must be filled when I hit the "Next" button?

My current code:

Private Sub cmdNext_Click()
If txtProjectTitle = "" Then
MsgBox "Please enter Project Title"

If txtDate.Text = "" Then
MsgBox "Please enter a date"

If txtProjectDuration = "" Then
MsgBox "Please enter Project Duration"

If txtClientName = "" Then
MsgBox "Please enter Client Name"

Else
frmPriceMaster.Hide
frmList.Show
End If
End Sub

Currently it gives me a "Block if without end if" error. Can someone help me? Thanks.

Help please

Thanks, got it!