Unable to create the validation at Call up point 3

Dear Friends,

I am trying to create the validation rule for call up point 3..

while doing the prerequisite is system is not througing any error message, But while doing Check step I am getting the message like " Formula composed upto first systax error"

This is the full length message i am getting the error..

The formula was composed up to the first syntax error.

Message no. GB 506

Diagnosis

You tried to exit insert mode, which is only possible if the formula has no syntax errors from beginning to end. If it is not, a new insertion session is opened ahead of the first syntax error. You can then correct the syntax error at the new position through making new entries or by deleting the formula symbols that follow.

You can then try exiting the insertion session again.

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Validation is

BKPF-TCODE = 'MIRO' and BKPF-BUKRS = '2005'

check

BSEG-BVTYP not equal to null

in this point i am getting the above mentioned message

Please let me know in this regard.

Regards,

Anand