I can not use OPA548 over 1A, why?

Dear Sir:

I use OPA548 for a noninver Amplifier.

First, I use dual power supply +- 15V.

and Rcl use 0 ohm, mean pin4 connect to pin3 directly.

It mean I set the current limit to 5A.

But really It can not reach 1A, when I use the correct Load. and limited about 731mA.

Please help me to correct use OPA548

Thanks

Best Regards,

Stone Shih