Conditional Formatting on Card Visual that has Filters using Measure in the Field

Hello Friends,

I have a Card Visual that is using a Measure (named: WorkItemCount) in the Fields and multiple Filters are applied. 

Internally the  WorkItemCount Measure using the below formula/column of the table:

WorkItemCount = 
var _workitems = COUNT('Table1'[Work Item Id])
return
IF(ISBLANK(_workitem), 0, _workitem)

The above measure is being used in multiple Cards and working as expected.

Now I want to change the forecolor of the card value to Green if the displayed result (post filter) is ZERO or else RED Color for any positive numbers. For this, I have used Field Value conditional Formating and used the Color Measure. 

Here is the Color Measure and formula:

Colour = 
var _workitems = SELECTEDVALUE('Table1'[Work Item Id])
var _forecolor = SWITCH(
TRUE(),
_workitems = 0, "#33AE81",
_workitems > 0, "#DC5B57")
return
_forecolor

I am not able to use  WorkItemCount Measure inside the Color Measure so I have used the Base Column [Work Item Id] which is used inside the WorkItemCount Measure. But this seems to work only for 0 and 1 values, but not for values that are greater than 1. Not able to find the issue or something wrong I am doing here.

Thanks,

Prabhat