Safe Link/safeSafe URI

Hi all, 

I have to realize a connection with an external browser page. I'm using this following code lines to insert into a sail page the click-able link:

a!linkField(
links:a!safeLink(
label:"Click here to open the new page",
uri:"significant://----------/SignificantAndroidAppLauncher.aspx?WorkstepId=------"
),
label:"Redirect to signature"
)

This is the error message:

Interface Definition: Expression evaluation error at function a!safeLink [line 25]: is not a permitted URI under the configured security rules and cannot be cast to safeUri.

How can i realize a working link to this kind of URI? It's not an http/https link, but a significant://... (it's a redirect link to a mobile application working on my mobile phone)

Thanks in advance

Andrew