Permission denied for table when querying in WebApp

Hi

in the Adobe campaign Classic v7. I am executing a query from the webapp when the user subscribe to get some reward code and inject into email . I am having permission issues when webapp trying to execute the query even though the webapp user have Administration rights( some time it works though) .. The webapp access control is set up as Anonymous access. The funny thing is that there is another query that gets execute fine. The table that is getting queried is under a custom schema .

below is the query that get executed

var query = xtk.queryDef.create( <queryDef schema="vb:promoCodes" operation="select" lineCount="1">
<select>
<node expr="@promoCode"/>
<node expr="@codeStartDate"/>
<node expr="@codeEndDate"/>
<node expr="@id"/>
</select>
<where>
<condition expr="@codeStartDate <= GetDate()"/>
<condition expr="@codeEndDate >= GetDate()"/>
</where>
</queryDef>)

var promoCodes = query.ExecuteQuery();

error below

Error | Function getpromoCode() failed | PGS-220000 PostgreSQL error: ERROR: permission denied for table vbpromocodes .

SOP-330011 Error while executing the method 'ExecuteQuery' of service 'xtk:queryDef'