Parameter not feeding to sub report

Hi

I have a report that has a sub report.

The report has a multi select parameter called 'Location', which linked with the sub report.

If I select just one option in the multi select, this is ok.

However, if i select two options, only the 'first/upper' selection feeds to the report..........

For example;

• London
• Manchester
• Paris

If I selected just Paris, the data would be ok. However, if I selected Manchester and Paris, only Manchesters data would push through.

Any ideas why? (Pretty basic with this.... so easy to understand answers would be GREATLY appreciated!!!!)