I am using the FieldConvert module as a FILTER in my session file. I noticed that not all of the modules are working. So far I found removefield and fieldfromstring to be not working. I paste below how I set the FILTER. For removefield it gives "Field does not exist" error, and for  fieldfromstring the code exits. I think both of the problems are related to the field variables. For removefield just add removefield:fieldname="u" .On the other hand, vorticity and gradient modules work. Has somebody  noticed a similar problem, or have I made a mistake while setting the filter? Thank you in advance for your help.

<FILTER TYPE="FieldConvert">
    <PARAM NAME="OutputFile">timeSteps/fcFiles/out.chk</PARAM>
    <PARAM NAME="OutputFrequency">1.0e+01</PARAM>
    <PARAM NAME="Modules"> vorticity gradient fieldfromstring:fieldname="dist":fieldstr="sqrt(x^2+y^2)" </PARAM>
</FILTER>