关于 ocserv 的证书验证问题，anyone can help me?

[windblueos]

根据ocser的官方教程，我创建好ca server以及client证书，并通过
certtool --verify --load-ca-certificate ../ca-cert.pem --infile user-cert.pem

Loaded 1 certificates, 1 CAs and 0 CRLs

Subject: CN=marlonlu,OU=admins
Issuer: CN=digitalocean CA,O=digital ocean
Checked against: CN=digitalocean CA,O=digital ocean
Output: Verified. The certificate is trusted.

Chain verification output: Verified. The certificate is trusted.

验证user-cert.pem是有效并且可行的证书，但为什么我把user-cert.pem导出p12格式的证书，ocserv反而提示
GnuTLS error (at worker-vpn.c:732): No certificate was found


我利用上一条命令去校验p12证书时：
certtool --verify --load-ca-certificate ../ca-cert.pem --infile key.p12
校验p12格式的证书，也是提示类似问题
error parsing CRTs: No certificate was found