The DS7000 is not receiving the DS10A's heartbeat. The DS10A sends its status about every 60 minutes or so, the MS10As send it about every 90 minutes (plus or minus a few minutes). Those signals let the DS7000 know that they're still alive.
You've got to either re-position the DS7000, move the DS10A (higher-up on the window), try a passive antenna on the DS10A (do a search here), or get a device that repeats the RF signal (like an SR731).
I had the problem, tried the passive antenna, but settled on an SR731. If you're only doing the DS7000 and not AHP, the SR731 is the way to go, but if you use AHP, beware that you'll get, and have to deal with, the possibility of multiple signals. For instance, one of my centrally located motion sensors sends a signal - The CM15A picks it up directly, as do both of my SR731'a, so AHP gets the same signal 3 times.
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