What is wrong with my exression it doesnt seem to work.
 

Cwaist is all the bones gouped so its pivot is in the orgin
rfoot and lfoot are my control foot bones. and im tring to gey the waist to say inbetween the feet. so when i move a foot forward the body stays inbetween rfoot and lfoot.

here is my expression

Cwaist.tx = (rfoot.tx + lfoot.tx)/2;
Cwaist.ty = (rfoot.ty + lfoot.ty)/2;
Cwaist.tz = (rfoot.tz + lfoot.tz)/2;
Cwaist.ry = (rfoot.ry + lfoot.ry)/2;

here is my error

expression -s "Cwaist.tx = (rfoot.tx + lfoot.tx)/2;\r\nCwaist.ty = (rfoot.ty + lfoot.ty)/2;\r\nCwaist.tz = (rfoot.tz + lfoot.tz)/2;\r\nCwaist.ry = (rfoot.ry + lfoot.ry)/2;" -o "" -n "Cwaist_expression" -ae 1 -uc all ;
EEnodeAdded Cwaist_expression;
// Error: More than one attribute name matches. Must use unique path name: rfoot.tx //
// Error: More than one attribute name matches. Must use unique path name: lfoot.tx //
// Error: More than one attribute name matches. Must use unique path name: rfoot.ty //
// Error: More than one attribute name matches. Must use unique path name: lfoot.ty //
// Error: More than one attribute name matches. Must use unique path name: rfoot.tz //
// Error: More than one attribute name matches. Must use unique path name: lfoot.tz //
// Error: More than one attribute name matches. Must use unique path name: rfoot.ry //
// Error: More than one attribute name matches. Must use unique path name: lfoot.ry //
EEnodeRemoved Cwaist_expression;

im at a loss i have no idea what im doing wrong. Thanks.

A wild guess: Have you tried using "translateX" instead of "tx" and so on?

ya and its still a "no go" :(

You probably have more than one object named lfoot and rfoot.
The err msg is asking you to specify their paths.

e.g.
character|rfoot.tx
|rfoot.tx (in this case, rfoot is a root joint)

ya on my geometry it had a rfoot lfoot name. So i called the joints clfoot crfoot for control. Thanks for the help.