Call a function in an 'If' statement vb .net

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VB

I want to call a function in an 'If' statement, I have done this before but it was different. This is how I did it before:

If Not validatePhone(txtContactNumber.Text) Then 
......
End If

That is straight forward for me because I know what to put in the brackets, but I want to call a function that checks that a database:

If Not checkDatabaseExists() Then
......
End If

I do not know what parameters go into the brackets here. This is the code for the function 'checkDatabaseExists':

Public Shared Function checkDatabaseExists(ByVal server As String, ByVal database As String) As Boolean
        Dim conString As String = ("Data Source=.\SQLExpress;Initial Catalog=Visitors;Integrated Security=True;MultipleActiveResultSets=True")
        Dim cmdText As String = ("SELECT * FROM master.dbo.sysdatabases WHERE Name=Visitors")
        Dim databaseExists As Boolean = False
        Using sqlConnection As SqlConnection = New SqlConnection(conString)
            sqlConnection.Open()
            Using sqlCmd As SqlCommand = New SqlCommand(cmdText, sqlConnection)
                Using reader As SqlDataReader = sqlCmd.ExecuteReader
                    databaseExists = reader.HasRows
                End Using
            End Using
        End Using
        Return databaseExists
    End Function

Can anyone help me? I know it's something simple and I'll be kicking myself when I find out what it is but I haven't a clue at the moment unfortunately. All help with this matter would be greatly appreciated.

Edit:

I get the following error without having parameters in the checkDatabaseExists() part of the 'If' statement:

'Argument not specified for parameter "database" of "Public Shared Function checkDatabaseExists(ByVal server As String, ByVal database As String) As Boolean" '