Can't get SID from DACL - winapi

Question

I am trying to get the DACL of service, and then get the SIDs. Here is my code:
PSECURITY_DESCRIPTOR psd = NULL;
DWORD dwSize = 0;
DWORD dwBytesNeeded = 0;
BOOL bDaclPresent = FALSE; // tu Trua mashin aq DACL
PACL pacl = NULL;
BOOL bDaclDefaulted = FALSE;
PEXPLICIT_ACCESS bevri = NULL;
ULONG aq = 0;
char ** gio = NULL;
serviceManager = OpenSCManager(NULL, NULL, SC_MANAGER_CONNECT);
SC_HANDLE me = OpenService(serviceManager, serviceName, READ_CONTROL);
if (serviceManager == NULL)
{
fprintf(fp, "OpenService: fail %d\n.\n", GetLastError());
fflush(fp);
}
if (!QueryServiceObjectSecurity(me, DACL_SECURITY_INFORMATION, &psd, 0, &dwBytesNeeded))
{
if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
{
dwSize = dwBytesNeeded;
psd = (PSECURITY_DESCRIPTOR)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, dwSize);
if (psd == NULL)
{
fprintf(fp, "HeapAlloc failed\n");
fflush(fp);
}
if (!QueryServiceObjectSecurity(me, DACL_SECURITY_INFORMATION, psd, dwSize, &dwBytesNeeded))
{
fprintf(fp, "QueryServiceObjectSecurity failed %d\n", (int)GetLastError());
fflush(fp);
}
}
else
{
fprintf(fp, "QueryServiceObjectSecurity failed %d\n", (int)GetLastError());
fflush(fp);
}
}
if (!GetSecurityDescriptorDacl(psd, &bDaclPresent, &pacl, &bDaclDefaulted))
{
fprintf(fp, "GetSecurityDescriptorDacl failed %d\n", (int)GetLastError());
fflush(fp);
}
if (GetExplicitEntriesFromAcl(pacl, &aq, &bevri) != ERROR_SUCCESS)
{
fprintf(fp, "GetExplicitEntriesFromAcl: failed %d.\n", (int)GetLastError());
fflush(fp);
}
for (ULONG i = 0; i < aq; i++)
{
if (ConvertSidToStringSid(&bevri->Trustee.ptstrName[GetTrusteeForm(&bevri->Trustee)], gio) == 0)
{
fprintf(fp, "ConvertSidToStringSid: failed %d.\n", (int)GetLastError());
fflush(fp);
}
for (int index = 0; gio[index] != NULL; index++)
{
char * myString = gio[index];
fprintf(fp, "Value: %s\n",myString);
}
}
I've read in documentation that GetTrusteeForm function would indicate if Trustee has SID or name, it returned 0s which in TRUSTEE_FORM indicates to TRUSTEE_IS_SID. My problem is that I have ConvertSidToStringSid: failed 87. which is The parameter is incorrect.. I can't figure out why am I getting this. P.S. I'm sorry I know that this part of code is not really helpful to reproduce the issue, but I thought someone might knew what would problem be. Any help would be appriciated. Thanks.