Help with countifs formula

I am a bit new to complex formulas so hoping someone can help.  I am trying to add a column on one sheet, that falls into two basic categories on the same sheet.  The formula I am using is as follows  =COUNTIFS({MM Non Prod Issue Tracking System}, [Distinct System]@row, {MM Non Prod Issue Tracking Days Old INT}, <=30, =[down time]@row)

MM NON PROD ISSUE TRACKING is the main sheet.  the columns I need are System from main sheet, Days Old INT less than 30 and I am trying to add all the downtime rows that meet my criteria.  DISTINCT SYSTEM is on the sheet I am trying to use my formula to calculate for only that system.

Little more info.  MM NON PROD ISSUE TRACKING Sheet has multiple systems based on days since September 1st, where they reside (INT or STG) and the time they were down then up (calculated by downtime).  

The answer I am trying to get to is System A, had 4 issues in the last 30 days in INT for a total of 75.  The 75 is what I am trying to total (the 4 issues were 50, 10, 10, and 15 lets say).  

Any help would be great.