Can't get Rear Audio jacks to work While cable connected to front jack

I am fairly new with W7 so please excuse my inexperience with this.

I have headphones connected to front headphone jack (Dell Inspiron 560 W7 Home 64). I want to have cable connected to rear jack (for speakers in other room). I can't get audio from the rear if anything is connected to the front jack. I do get about one second with the rear pink jack and the yellow jack - but not the green jack - but after one second it stops.

The sound card is RealTek High Definition Audio, driver from 10/09 Vers 6.0.1.5963.

Note that when making a similar connection to my XP machine the RealTek card/jacks do play in both front and rear at the same time.

I have attached screenshots of the Control Panel ->RealTek image (annotated with mouseover text) and the Volume->Properties image.

I do a lot of support on the Dell users forum. Dell uses a custom implementation of the RealTek audio, only the Dell RealTek audio drivers will work or work properly. Some models of the RealTek audio chip have the capability to do what you want and some do not, on others it's up to the PC/Motherboard vendor whether to implement certain functions or not. It may be possible but I don't recall seeing any posts on the Dell forum about this particular item.

Usually, the default setup is to mute the rear connected speakers when a headphone (or whatever) is plugged into the front headphone jack.

Here is the Dell on-line manuals for the 560/570 models
http://support.dell.com/support/edocs/systems/insp560mt/en/index.htm

This is as said, by design.
You may be able to switch off front sensing using the small icon just above the "analog" on your screenshot - this may solve the issue.

If not its a case of physically disconnecting the jack sensor inside the case, or the use of a splitter to connect both required outputs to the rear jack socket. Not eligent, put practical

Thank you fireberd and Barman58 for your replies.

At least I know that it is not something that I am doing wrong. It's just another case of B.A.D. (Broken As Designed) code, this time by Dell.

Thank you for your help - it is appreciated