If you don't presently have a phase coupler installed at your electrical panel, that is at least part of the problem. All homes require a phase coupler for reliable X-10 operation. Moving transmitters and receivers to different parts of your home can sometimes help, but it is a "band aid" solution. I recommend the use of an amplified phase coupler/repeater. Please see my posts in other threads on this forum where I have described the benefits of this product.
The other potential problem is line noise near your IR543. Many times the amplified phase coupler will take care of moderate line noise. If not, then individual noise suppression modules are available to take care of that.
We offer all of the products I mentioned, and a complete line of other home automation gear.
Robert
RCI Automation
[email protected][Link: ourworld.compuserve.com]