getting space in expected result

below is the assertion:-

${=(${Retrieve Initiator Details#ResponseAsXml#//Results[1]/ResultSet[1]/Row[1]/MPG_FUNDING_ACCTS.RTA_FUND_PAN[1]}).toString().substring(0,6)}******${=(${Retrieve Initiator Details#ResponseAsXml#//Results[1]/ResultSet[1]/Row[1]/MPG_FUNDING_ACCTS.RTA_FUND_PAN[1]}).toString().substring(12,16)}

In expected results i am getting one empty space at the last. I tried astric (*) at the end and checked wildcard but it didnt work.

The XPath Match assertion failed for the following path: [//isomsg[1]/field[@id=2]/@value]. Expected value: [527109******2009* ]; Actual value: [527109******2009].