css for overlapped window seems not work

I want to set the title text of the window to 28px and align to center,
these css code was gen-by zk studio 0.9.5

---

<style>
.myname6 .z-window-overlapped-header .z-caption .z-caption-l, .myname6 .z-window-overlapped-header .z-caption .z-caption-r {
font-size : 28px;
text-align : center;
color : #000000;
}

.myname6 .z-window-overlapped-cnt, .myname6 .z-window-overlapped-cnt-noborder{
background-color : #FFFFFF;
}</style>

---

<window sclass="myname6" title="large font"/>
but it seems not work when i overlapped the window.

by the way , i specified css for a label , code gen-by css designer is :

---

<style>
.printtitle.z-label {
font-size : 28px;
font-weight : bold;
}
</style>

---

the former code dosen't work too,but if i change it to the following code, it works:

---

<style>
.z-label.printtitle { font-size : 28px; font-weight : bold; }
</style>

---