JDBC connection problems (to mssql server)

Hi all,
I have searched through the forums for similar issues and I have gone through all supposed solutions but no resolution yet.

I am using the trial version of Soap UI Pro and I'm trying to connect to MsSQL server via JDBC (tried both Datasource and Groovy script) and they both complain about not finding a suitable driver when I have copied the jar file in soapui/bin/ext (and jre/lib/ext and also in soapui/lib).

This is the driver and string I'm using:
com.microsoft.jdbc.sqlserver.SQLServerDriver
jdbc:microsoft:sqlserver://SQLDEV:1433;databaseName=MyDB?user=USER&password=PASSWORD

I am receiving that error:
Thu Nov 08 15:42:45 EET 2012:ERROR:com.eviware.soapui.support.SoapUIException: Failed to init connection for drvr [com.microsoft.jdbc.sqlserver.SQLServerDriver], connectionString [jdbc:microsoft:sqlserver://SQLDEV:1433;databaseName=MyDB?user=USER&password=PASSWORD]
com.eviware.soapui.support.SoapUIException: Failed to init connection for drvr [com.microsoft.jdbc.sqlserver.SQLServerDriver], connectionString [jdbc:microsoft:sqlserver://SQLDEV:1433;databaseName=MyDB?user=USER&password=PASSWORD
at com.eviware.soapui.support.jdbc.JdbcUtils.initConnection(JdbcUtils.java:64)
at com.eviware.soapui.impl.wsdl.support.connections.DefaultDatabaseConnectionContainer.testDatabaseConnection(SourceFile:271)
at com.eviware.soapui.impl.wsdl.teststeps.datasource.JdbcDataSource$TestConnectionAction.actionPerformed(SourceFile:283)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)

I have tried the same using the free version of Soap ui, but the same error is returned.

I would appreciate any advice.

Thanks,
Diliana