Appeal from an amended order of the Supreme Court (Reilly, Jr., J.), entered March 12, 2002 in Schenectady County, which denied defendant’s motion for summary judgment dismissing the complaint.
Shortly after arriving at work on the morning of September 13, 1994, plaintiff Gail Smith (hereinafter plaintiff) entered a file room and slipped on a “slick, oily, greasy substance.” Plaintiff and her husband, derivatively, commenced this personal injury action against defendant, the janitorial service that cleans plaintiff’s workplace, alleging, inter alia, that it had created the dangerous condition and had actual and constructive notice of the condition. Following joinder of issue and discovery, defendant moved for summary judgment dismissing the complaint. Supreme Court denied the motion, prompting this appeal.
We agree with Supreme Court’s finding that defendant, as proponent of the motion, satisfied its initial burden by showing that it “neither created the condition nor had actual or constructive notice of the condition” (Altieri v Golub Corp., 292 AD2d 734, 734-735). In our view, however, plaintiffs have not *875met their shifted burden by raising triable issues of fact (see Dapp v Larson, 240 AD2d 918, 918). Notably, plaintiffs have failed to submit affidavits of anyone with knowledge of the identity of the “slick, oily, greasy substance,” its source or how long the substance had been on the floor before the accident. Instead, the evidence discloses that the unidentified substance could have been dropped by anyone with access to the premises. It is unclear whether any other employees worked late on the evening of September 12, 1994 and entered the file room after it had been cleaned. Plaintiff, in fact, concedes that the source of the substance could have been someone other than a cleaning person. Because “conclusions based upon surmise, conjecture, speculation or assertions are without probative value” (Maiorano v Price Chopper Operating Co., 221 AD2d 698, 699; see Dapp v Larson, supra at 919), we find that plaintiffs’ proffer simply is insufficient to raise a triable issue as to whether defendant created the dangerous condition or had actual or constructive notice of it. Accordingly, we reverse Supreme Court’s order and grant defendant’s motion for summary judgment dismissing the complaint.
Crew III, Spain and Carpinello, JJ., concur.