NULLIF problem

HELLO,<br /><br />I encounter an error if i use NULLIF with timestamp with time zone.<br />eq.
dbtime=nullif(mytime,'')<br/><br />i want to null the value of field DBTIME if the variable mytime=" "<br /><br
/>DBTIME="timestamp with time zone" datatype <br /><br />error: column DBTIME is of type timestamp with time zone but
expressionis of type text.<br /><br />What should i do?<br /><br />Thanks in advance...<br clear="all" /><br />-- <br
/>GeraMel E. Handumon<br />Application Programmer <br />PaySoft Solutions, Inc.<br
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