why does breast physics not work on my avatar

[zaylene]

why does breast physics not work on my avatar?

[valerie Inshan]

Because your bra is too tight?

More seriously, make sure you entered the correct settings and saved them. :smileyhappy:

http://community.secondlife.com/t5/English-Knowledge-Base/Controlling-your-avatar-s-appearance/ta-p/700709#Section_.3.1

[Rolig Loon]

Breast physics was introduced with V2 coding of viewers a couple of years ago.  If you are using an older, V1-style viewer, it may not be capable of handling breast physics. 

Breast physics is also a purely client-side effect.  That is, the effect is generated by your own graphics card, not by SL's servers.  You may have a graphics card (or, if you are on a laptop, a graphics chip) that cannot produce the effect well, especially under heavy load.  This might be particularly true if you are experiencing much lag.