Blessing of protection for healing priests

If you have a priest as a healer in an instance, he generally protects himself with a shield if the tank loses aggro for some reason. If the mob is untauntable or righteous defense is resisted, the only thing a pally can do is to cast Blessing of Protection to the healer. This can't be done if the target has a weakened soul debuff from the shield. Do you instruct priests to avoid using the power word: shield until it is absolutely necessary? I haven't used Blessing of Protection often, because it often doesn't work and I realized that PWS might be the reason for it.

PW:s shouldn't affect BoP, if it does, it's clearly a bug.
http://www.wowwiki.com/Weakened_Soul

"A debuff that affects targets of Power Word: Shield spell. Until this effect fades, the target cannot have Power Word: Shield spell cast on them again.

This debuff lasts 15 seconds, and cannot be dispelled. "

I've never had any problems with casting BoP on anybody.
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Theorycraft is the last thing that is gonna help you kill a boss. Yes i will get 20 dps more or tank will get 20 TPS more, but that doesn't kill bosses, playing smart and good while being ready to improvise is what does the job.

Ok, I guess my macro is just screwed up or something. Sorry about hassle.