Reference to table in different workbook is inconsistent?

[Xalova]

So... basicly what the title says.

I have a formula which lets me filter values from a huge table as a database. the formula is as follows:

=LET(Advanced,
IFS(F2<>"",SEARCH(F2,'Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[Lieferant]),H2<>"",SEARCH(H2,'Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[Artikel-Nr.]),J2<>"",SEARCH(J2,'Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[Material]),L2<>"",SEARCH(L2,'Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[Kategorie]),N2<>"",SEARCH(N2,'Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[Norm])),

FilterName,
FILTER('Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[#Data],ISNUMBER(SEARCH(C2,'Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[Name]&'Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[Synonym, Beschreibung A+L])*IF(ISERR(Advanced)=FALSE,1,Advanced)),

"keine Artikel vorhanden"),IF(FilterName=0,"-",FilterName))

that works as long as i have the databasefile open. But i need it to be independent from eachother. i thought that maybe the filter function causes the problem. So i thought only reference the table in the other workbook.
with

='C:\Users\t.schroeder\Desktop\btry\Verbrauchsmaterialien Datenbank (work in progress).xlsm'!Verbrauchsmaterial[#Data]

as soon as i close the workbook "Verbrauchsmateirlien Datenbank (work in progress)" i get a ref error. Why is it and how do i fix it?

 

[Fluff]

Try using ranges rather than structured references.