Loss/Wrong custom field data

Hi All,

When i get the document data by using "getItemRequest", that responses the custom field data will be loss or wrong.

For Example:

<field>custom field A</field>
<value>aaa</value>
<field>custom field b</field>
<value>bbb</value>

it will response.....

<field>~8010</field>
<value>0</value>
<field>custom field b</field>
<value>bbb</value>

or response......

<field>custom field b</field>
<value>bbb</value>

Am i missing something or step?
Or what i need to do?

Thanks a lot

Jim