lost transmitter errors

Hi everyone
 
I have an Elk security system. I've had it for several years now and for the most part it's been working fine. In the last month or two or so I have suddenly been getting lost transmitter error on the keypads. At first it was one, then 2, and now it's about 6 or 7. I replaced the battery on a couple of them and they seemed ok for a while, but now they are doing it again.
 
Can you explain exactly what this supervision loss means? Do I need to get new sensors to replace the ones that have failed?
 
Thanks for your advice
 
Matt
 

What types of wireless transmitters do you have, and what batteries did you use to replace the old ones? 

They are GE sensors. I used the same batteries that came in them. I don't recall the number off the top of my head.

The reason I was asking about the batteries is because your description that replacing the batteries fixed the problem for a while makes me think that it is simply due to bad or weak batteries.  If you aren't using a brand-name battery like Duracell or Energizer, I would try some of those.  But even with brand names, on occasion, I've run into stale batteries that didn't last long.

Supervision errors lead me to believe the issue, while batteries may be plausible, I would start looking at the RF receiver and location of it....

What's odd about all this is they worked fine for years, then suddenly a bunch of them started acting like this.  Other sensors are fine. The batteries are Maxell brand. Got them from Amazon. I think I will order some new sensors and give them a try. These are the sensors I'm using:
 
http://www.amazon.com/MICRO-DOOR-WINDOW-SENSOR-WHITE/dp/B00070LZ4I
 
Are there better ones?
 
Thanks for all the help
 
Matt

Typically the GE sensors send a supervision signal about ever 55 minutes.  I usually get a supervision error is a signal is missed for 5 or 6 hours.  Although I have read conflicting things, the GE senors don't seem to send out a low-battery signal, or at least my receiver doesn't seem to report it.  I have many receivers that are 8 years+ and they have yet to have low battery, with the exception of GE smoke alarms which only seem to last a year or two on batteries.
 
An increase in supervision problems my NOT be low batteries. It could be interference.  Note that with GE sensors, they also sell a repeater, which isn't bad to use for a bigger house. I have one and its always helped.
 
Are the supervision errors occuring to senors in the same general area, or with all sensors?  If all sensors, the interference might be near your receiver.  Do they happen at a certain time of day?  Have you changed or added anything in the house lately? 

Isn't metal an issue? Perhaps you stuck something adjacent or in vicinity that is blocking the signals.

The misbehaving sensors are pretty spread out: basement and garage, which made me suspect distance since they are the furthest away, but one or two in the kitchen and dining room are doing it as well. I have the receiver laying on the floor in a storage room. I have not added or moved anything, but I think I'll try placing the receiver in a better position and see if that helps at all.
 
Matt

I ended up getting new sensors and they are working fine. I took one of the old ones that was acting up and tried using it closer to the receiver and it failed there too, so I guess they just went bad after time. That's a pain, but now after replacing them everything is working fine.
 
Matt