Left locator in position bar is locked

[rbarata]

Hi

I'm using Arturia Storm 3 rewired with Cubase SX1.03 .
My question is that I need to make a loop but can't put the left locator where I want. In Arturia it simply goes one bar after or one bar later from the place where I want it.
In Cubase, I can place it where I want but when I press "Play" it goes again to the original place.
it seems that this locator is being locked by Cubase...

Any tips?

Thanks

Rui