How to rewrite an Impromptu case statement in Cognos Framework Manager?

Question

I have a case statement in Impropmtu that I need to recreate in Framework Manager. I need help with case statement syntax in Framework manager, and in this special case, there is a nested statement involved that makes it a bit more complicated.

I tried using the predefined components in Framework Manager to create the case statement but it doesn't work. I am thinking maybe it is because of the syntax.

This is the Impromptu expression from *.IQD file:

 CASE 
 WHEN  ((CASE 
 WHEN ((((((((('D12' || "ACCOUNT1") = 'E4GM') or 
 (('D12' || "ACCOUNT1") = 'E4M')) or 
 (('D12' || "ACCOUNT1") = 'DAM')) or 
 (('D12' || "ACCOUNT1") = 'DGM')) or 
 (('D12' || "ACCOUNT1") = 'DJM')) or 
 (('D12' || "ACCOUNT1") = 'DNM')) or 
 (('D12' || "ACCOUNT1") = 'DQM')) or 
 (('D12' || "ACCOUNT1") = 'DWM'))
 THEN ('Units') 
 ELSE null END) = 'Units') 
 THEN (CASE 
 WHEN ("MODEL" BETWEEN '10%' AND '19%') THEN ('Mini Unit') 
 WHEN ("MODEL" BETWEEN '21%' AND '22%') THEN ('Small Unit') 
 WHEN ("MODEL" BETWEEN '32%' AND '33%') THEN ('Medium Unit') 
 WHEN ("MODEL" BETWEEN '38%' AND '39%') THEN ('Large Unit') 
 WHEN ("MODEL" BETWEEN 'M3%' AND 'M4%') THEN ('WH Unit') 
 ELSE null END) ELSE null END as c21,