Importing soapUI-trial.key says "License is invalid".

I have Downloaded a Trail version and i have got the License.zip in my mail id. When i m Trying to import the extracted file (soapUI-trial.key), it says "License is Invalid", i m using Soapui Pro 4.0.0 version.

Please help me i want to try this tool, heard a lot about this tool.

Thanks.