MS-SQL: Getting error "Error converting data type varbinary to numeric"

I've got a trouble with deleting/updating the particular row in my table. The table is small and simple:

CREATE TABLE dummy (
    "numemv" NVARCHAR(50) NOT NULL DEFAULT NULL,
    "control_summ" DECIMAL NOT NULL DEFAULT NULL,
    "active" CHAR(1) NOT NULL DEFAULT '1',
    "departid" INT NOT NULL DEFAULT NULL,
    UNIQUE INDEX "UNIQUE" ("numemv")
)

The row that I can't delete/update:

numemv   control_summ active departid
00499038 400000       1      0

I tried to manage in this ways:

UPDATE dbo.atm_control_summs SET departid = 13 WHERE departid = 0
DELETE FROM dbo.atm_control_summs WHERE departid = 0
UPDATE dbo.atm_control_summs SET departid = 13 WHERE numemv = '00499038'
DELETE FROM dbo.atm_control_summs WHERE numemv = '00499038'

But always I get the error: Error SQL (8114): Error converting data type varbinary to numeric.

How can I fix this error?

Thanks in advance :)