Change source data of chart by adjusting two cell values

Thanks for the fast help,

but neither seems to work. If I put either of the proposed options in the Y.values slot, it directs me to the correct part of data on the correspondig sheet. But as soon as I press Enter to accept, it keeps giving me the error message

Any advice?

PS: It should be an xy scatter plot with two measurements in each diagram with corresponding x and y values.

P1.jpg