Nested if blank statement

[pasele]

COSTCENTER_fix = 

IF(
    ISBLANK('sapdata SAP_generalaccounting'[COSTCENTER]),
    IF(
        ISBLANK('sapdata SAP_generalaccounting'[WBS_ELEMT]),
        'sapdata SAP_generalaccounting'[PROFIT_CTR],
        LOOKUPVALUE('sapdata SAP_projektelement'[Ansvarigt_kostnstl], 'sapdata SAP_projektelement'[WBS_element], 'sapdata SAP_generalaccounting'[WBS_ELEMT])
    ),
    'sapdata SAP_generalaccounting'[COSTCENTER]
)

Here is my current code that is not working.

I want to check if column COSTCENTER is blank 
if it is blank use values from LOOKUPVALUE from WBS_ELEMNT
and if both are blank I want the values from PROFIT_CTR

problem is values from profit_ctr are not being entered, if both are blank this column is also blank. I cannot have blank rows in this column

[wdx223_Daniel · Accepted solution]

may there are some non-true blank values in the column of WBS_ELEMNT

[pasele]

Ah yes you are correct, now that I checked it is just no text instead of (blank). What would be the best way to fix this? 

[wdx223_Daniel]

'sapdata SAP_generalaccounting'[WBS_ELEMT]=""