It just means you aren't strong enough to handle the 26lbs, yet.
Slowly work on your shoulder, arm, forearm, and wrist strength.
You will find playing with higher tension gives you better control over your shots.
Smashes will be faster, drop shots will be steeper, and net shots will be tighter.
And best of all, the sweet sound of a full-blown smash, is much much sweeter on a high tension-ed racket.

Also, string tensions drop over time, work the 26lbs strings alittle, it should drop down to 24lbs or 25lbs in no time.

Me personally favours 29lbs or so, but since there will be a drop in tension over time, i usually string mine at 30 or 31lbs, if the racket can take it.