I think the problem that you are experiencing has to do with a few SQL express configuration settings that you would need to configure before attempting to use the OnTime windows client. We have noticed that remote SQL connections must be enabled for the SQL Express instance in order for the OnTime application to properly connect to the SQL server. The link following link will take you to our OnTime FAQ section where this problem is mentioned. Please follow the necessary steps within the Microsoft knowledge based article on how to enable remote connections for SQL Express.

How to enable remote connections for SQL 2005\Express

http://community.axosoft.com/forums/thread/10898.aspx

Thank you,