SAP WEB IDE: No connect possible to remote system (on premise)

Hello

I've tried to follow the steps according to

http://scn.sap.com/community/developer-center/front-end/blog/2015/02/11/set-up-your-sap-web-ide-on-hana-cloud-part-1

At part 3 "Connecting to remote system" the

At part 4 " test the SAP Web IDE" when browsing the service catalog, I can select my system LAB (which I've maintained according to part 3 "Connecting to remote system". LAB is a on premise ABAP system and in the hana cockpit the destination shows status green, which means

it can be reached through the sap hana connector.)

Now the following problem arises: "unable to access the selected system. check credentials and try again".

However the provided credentials are ok.

I've tried also to debug according to http://scn.sap.com/community/developer-center/front-end/blog/2015/02/13/troubleshooting-sap-web-ide-destination-issues , but no success.

Is there a better way to tackle down the connection problem, a step by step guideline?

Thanks for your feedback.

KInd regards

Chris