Car does not accelerate up hill

[RaviH]

I recently bought a 2007 Suzuki Swift (Japan beetle model) 1.3 cc Automatic car. My parking area is on a slope surface and every time when I start the car I need to climb a hill to hit the road. The problem is the car does not accelerate properly on that up hill surface. It's only an average hill surface. I slow down the car in the middle of the hill & tried with 'Low' gear, and even with that the car didn't move. I pushed accelerator but the RPM won't go above 2000.

But when I reverse car back to the parking area and accelerate at once, the car climbed the hill with speed. This issue only comes when I start the engine and tried to hit the road in that uphill area.  I tried replacing Auto Transmission Fluid, but the issue still is there.

I don't have much experience on driving and vehicle related stuff. Therefore, I want to know whether this is really a problem with the engine/gearbox or  this is usual in automatic cars. Dear members please help to sort out this.. Thank you.