error C2110: cannot add two pointers

if (GetDlgItemText(IDC_DOMAIN, szText) == 0)
{
throw_snapin_error(sMethodName, E_FAIL);
}
if (GetDlgItemText(IDC_DOMAIN_1, szText1) == 0)
{
throw_snapin_error(sMethodName, E_FAIL);
}
if (GetDlgItemText(IDC_DOMAIN_INC, szText2) == 0)
{
throw_snapin_error(sMethodName, E_FAIL);
}
// Merging the String back
wchar_t *str=L",";
szText += str + szText1 + str + szText2;

in the above line i am concatentating two strings and when i do this i get error saying cant two strings. Please can some one help?

here szText is a wchar_t pointer