How to add one more filter in Reference qual without impacting the previous added filter

[VIKAS MISHRA]

There is one reference field, where i can see already some conditions/filter is added as its an advanced type reference field. 

I do not want to change any already added filter and simply wants to add my one more condition.

condition is : that this reference filed should show the records where checkbox "u_added_to_project" is true.

However when i am adding my condition at the end of the reference qual condition then its not working but when i am adding my condition in mid of the already added condition then its working, please suggest what is the difference and why its not working when i am adding my condition at the end, and how can i add my condition so that it will not impact the earlier added condition.

Below is the screenshot where i added the heighlighted condition at the end where its not working 

Below is the reference qual where i have added this in mid and its working.

[SanjivMeher · Accepted solution]

You need to add that in quotes. System can evaluate current.top_task, but everything after that should be in quotes, since those are string and not variables.

current.top_task+"^u_added_project=true"