Voltage compliance issue in picoammeter 6487

I want to use the picoammeter 6487 for I-V sweep and resistance measurement. The voltage typically should go up to 500V but when I try to set the voltage source to 6.8V or higher, it gives voltage compliance error, even when it is open circuit (no cable is attached to it).

I tried several times to possibly find any way to increase this compliance limit via its menus and settings but no success. If somebody knows, please inform.

PS: I do not have GPIB for the moment. It seems that by coding, it is possible to modify the voltage compliance limit.

If you are seeing the OCOMP indicator when you turn the voltage source on, this means the maximum current (current limit) has been encountered.
If this occurs even for open circuit, I suspect some malfunction in the instrument, or your cabling is not what you think it is.

From front panel, you can adjust the amount of current limit.

Both the reference and user manuals detail the procedure.
 

From Reference Manual:

There is no issue with the maximum current, since the current limit is set to 25mA and the compliance error happens even at open circuit.

I am double checking whether it is an internal equipment issue or setting issue. I just received GPIB today and will double check whether it would make any difference if doing I-V measurement via GPIB.

The issue got resolved when I used voltage sweep using GPIB :)