The style 16 is not supported for conversions from varchar to date. It is supported for conversion of date to date only
You may use:
declare @verdate as char(10)='01-01-2014'
declare @secdate as date=getdate()
select datediff(DAY,CONVERT(date,@verdate,105), CONVERT(date,@secdate,105))
Bharat Narang
Microsoft Certified Solutions Associate in SQL Server 2012