the problem is you are entering multiple values for a parameter that only allows one value. You mentioned it works if you only set one value for each parameter. This makes sense. You can ONLY add multiple values to the Accounting Brand parameter (<id>1</id>) so your request should be more like:
<parameters>
<parameter>
<id>0</id>
<answer>
<values>
<value>761</value> <--Only a single value for this parameter
</values>
</answer>
</parameter>
<parameter>
<id>1</id>
<answer>
<values>
<value>BURDN</value>
<value>BRONI</value>
<value>CLIMT</value>
</values>
</answer>
</parameter>
</parameters>
Dan
