samsung A520f unlock error

Searching Samsung modem... detected COM95
Reading phone info... OK
Model: SM-A520F
AP version: A520FXXU4BRB1
CSC version: A520FEVR3BQL2
CP version: A520FXXS4BQLE
Product code: EVR
Phone SN: R58J2338XWP
Unique number: CBJ1022B5FC3714
Searching Samsung diag port... detected COM94
Reading phone info... OK
CP version: A520FXXS4BQLE
CP build: Dec 28 2017 15:36:45
Reading data from phone... error (1)
Searching server... OK
Checking available files... not found compatible file
Try downgrade modem if possible
Done with Samsung Tool PRO v.31.1



i try modem file from b3 version but base band unknown

sir any solution for this