I'm creating a report in MS SQL Server Reporting Services and need to set the default Start and End Date report parameters to be the first and last dates of the previous calendar month and need help.

The report is generated on the 2nd calendar day of the month and I need values for: 

> 
> Previous Calendar Month  
> 
>  - first day  
> 
>  - last day
> 
> 
> 

I've been working with DateAdd, but have not been successful at creating an Expression (in VB.NET as I understand it). I would really appreciate any help you can give me!