Formula URL with Case to open different forms

My goal is this:  when the user clicks the button, it will open a different form depending upon what type of issue the related record in the form has listed.  This is the formula I'm messing with but I'm not sure if I have the syntax right or if its even possible?

URLRoot() & "db/" & Dbid() &
Case([Issue],
"Query Opportunity and Potential Impact","?a=dr&dfid=13,
"Query Review","?a=dr&dfid=12,
"Process Review","?a=dr&dfid=11)
&rid=" & [Record ID#]

Thanks in advance!

-Audra Mickles