Variable baseline on a chart

[Jedi Topcat]

Hello All

I am trying place a variable baseline onto a Report studio chart.

When the prompt on the main page changes, I want the target on baseline to also change on the chart.

for example:
if([WIP/NCR].[Projects].[Model]='737') then (10) else if ([WIP/NCR].[Projects].[Model]='747')then (10) else if ([WIP/NCR].[Projects].[Model]='777')then (30) else (150)

I can force it to work by making the the baseline prompts:
if(?Model?='737') then (10) else if (?Model?='747')then (10) else if (?Model?='777')then (30) else (150)

And I have tried linking prompts to the main report to no avail.

Any ideas