Build doesn't start with prompt configuration parameter

Hello everyone,

We're using TC 8.1.5 and I have a problem with creating a prompt for a configuration paramter.
Basically what I want is for the user to select from a list of projects. The value from that list will be part of the path of the pom that the user wished to build.
So that path to the pom is defined as follows: %release.project%/pom.xml

When I try to start the build, I indeed get a prompt for the defined parameter but when I select something from the list and press Run Build nothing happens.

If, however I run a custom build and then select one of the options in the Parameters section it works fine. I have to mention that in the custom build there are 3 other paratmers shown, one of which is another prompt parameter that has a default value.

So... am I missing something here?

My parameters is defined like so:


Thank you very much,
Guy