Workflow url changes in email string builder

I have a problem with workflow as below:

Adding new item in the list need approve before open to the public and I created a workflow A (automatically initial after new post) which will send moderator an email containing a url of workflow B (manually initial, change the approve status to approve or reject). I build the url of workflow B in email in workflow A by String Builder, but the url in the String Builder changed and did not work after several clicks the url of workflow B in the email.

Specifically, Changed from "http://.../../../List={......}&TemplateID={......}" to "http://.../../../List=\\\{......\\\}&TemplateID=\\\{......\\\}". When the back slash accumulated to three, the link bread down.

Anybody have the similar problem before?

Thanks