Why Stored Procedure throws exception during transaction?

Hello everyone?

I will post in english but I am an spanish speaker!! So let's try to do this.....

I am stocked with an issue working with ado.net and sql server2009.

the problem is when i call a Store procedure that try to insert data into a column with a check

constrait. the insert is into a transaction block, but when i call the sp via ado.net y expect to receive 

the return value so that i can manage the process behaviour and send appropriate message.

but instead, after the sql command> executenonquery() method it throws the check column exception from sql server.

as it is into a transaction, i was expecting not to have an axception, and can filter via my return value.

with this exception, users receive very confidential information from the database structure, and even i can not indicate that the problem was just incorrect data format for that column value.

does anyone knows how should i configure sql server or app server with ado.net in order to not receive

(or throw...) that check constraint exception??

i have to add that this is an academy proyect, so that i am mandatory to use some architectures and technologies, but as i am stocked, i want to hear new options.

thanks in advance!!