SQL Server 2008/2012 - incompatible data types in comparison after cast/convert

SQL Server 2008/2012 table: StringNum varchar CharValue char DoubleNum decimal BigIntegerValue decimal ShortValue decimal FloatNum float ObjectValue text IntNum decimal BigDecimalValue decimal LongNum decimal BooleanValue bit TimestampValue datetime ByteNum decimal IntKey decimal StringKey varchar TimeValue time DateValue date Teiid table: INTNUM integer BIGDECIMALVALUE bigdecimal BIGINTEGERVALUE biginteger BOOLEANVALUE boolean BYTENUM byte CHARVALUE char DATEVALUE date DOUBLENUM double FLOATNUM float INTKEY integer LONGNUM long OBJECTVALUE object SHORTVALUE short STRINGKEY string STRINGNUM string TIMESTAMPVALUE timestamp TIMEVALUE time Queries: SELECT convert(TimestampValue, time) FROM <table> WHERE convert(TimestampValue, time) > '00:00:00' SELECT cast(TimestampValue as time) FROM <table> WHERE cast(TimestampValue as time) > '00:00:00'