WEAK RSA

when i tried to solve weak rsa the error shown below is displayed what should i do

root@kaliblue:~/HTB/RsaCtfTool# openssl rsautl -decrypt -inkey private.pem -in flag.enc -out key.txt

RSA operation error
139976077754560:error:0407109F:rsa routines:RSA_padding_check_PKCS1_type_2:pkcs decoding error:…/crypto/rsa/rsa_pk1.c:241:
139976077754560:error:04065072:rsa routines:rsa_ossl_private_decrypt:padding check failed:…/crypto/rsa/rsa_ossl.c:487:

pease help me to fix this error

so close ! read the error message and perhaps check that your private was correctly created from your public one.