Expected value type: end-of-string infopath configuing the main submit button on the form.

Hi Everyone,

so I have run into this very odd problem. When I am trying to configure my main submit for my infopath 2010 form, and it says File Name, I put in concat(field 1, field 2, field 3), and when the form submits, I get the following as a name for my form: field 1, field 2, field 3, exactly like that. so I went back into the main submit and typed concat( and then used the function button, which brought up the list of controls to choose from, so I choose field 1, field 2, field 3 and when I hit ok, I keep getting this error:

Expected value type: end-of-string

Actual value: ,
my:secReqMetaData/my:field 1-->,<-- my:secReqMetaData/my:field 2,my:secReqMetaData/my:field 3

does anyone have any idea why this is happening?

Best regards, Mike