Occasionally, the power will work as described. However, just as frequently, a message will be given through your character (similar to how your character "speaks" in the chat window when using any menu) that says:
"He looks at you for a moment, then turns back to what he was doing."
Simultaneously, the psionicist who used the power will say "hehe" above his head, preceded by an orange-colored system chat message (that also appears above the PC's head) which says:
"If you act quickly, you may be able to influence the to help you." (Sic; including extra space and typos)
Then, the system chat indicates you've used the power:
"You manifest Summon Planar Creature"
However, no creature appears, not even briefly before vanishing.