Bubble graph help

Hello,

I'm sure this is probably a very simple issue that I'm overlooking, but here goes:

I want to create a bubble chart which plots employees by their rating against two criteria ("Tasks" and "Behaviours", both on a scale of 0-10) with bubble size determined by job role.

I have a worksheet with the following info:

M18:M50 has the series' name
N18:N50 has the X-axis value ("Tasks")
O18:O50 has the Y-axis value ("Behaviours")
P18:P50 has the bubble size value (job role as a numeric value, 1-5)

When I try to create a Bubble Chart from that data, the Chart Wizard

When I correct this to

Series 1
Name: $M$18
X Values: $N$18
Y Values: $O$18
Sizes: $P$10

It displays exactly as I want it, but I have a lot of series and so can't do this manually for each. How can I get Excel to automatically recognise N18 as the X value, O18 as the Y value etc.?

I hope that makes sense, let me know if it doesn't. Thanks in advance for any help.