UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

Schedule 13D

Under the Securities Exchange Act of 1934
(Amendment No. 4)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of Secs. 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. ¨

Number of shares beneficially owned by each reporting person with:

Number of shares beneficially owned by each reporting person with:

Number of shares beneficially owned by each reporting person with:

Introduction

James L. Davis, a United States resident, the Davis & Associates, Inc., 401K PSP, a profit sharing plan and Davis & Associates Inc., a Minnesota corporation (collectively, the “Reporting Persons”) here by filed this Amendment No. 4 (this “Amendment”) to its Statement on Schedule 13D filed with the Securities and Exchange Commission on February 24, 2009 (the “Statement”) as amended by Amendment No. 3 thereto filed February 9, 2012 on behalf of the Reporting Persons identified in Item 2 of the Statement.

Items 4, 5, 6 and 7 of the Statement are hereby amended to the extent hereinafter expressly set forth. All capitalized terms used and not expressly defined herein have the respective meanings ascribed to such terms in the Statement.

Item 4. Purpose of Transaction:

The first paragraph of Item 4 is amended and restated to read:

The Reporting Persons acquired the Shares reported herein for investment purposes in private placements and public offerings by the Issuer. In his role as a Director of the Issuer, Mr. Davis receives an annual award of $25,000 of stock options upon re-election to the Issuer’s Board by a vote of shareholders, and earns directors fees that may be paid in the Issuer’s common stock. Since 2006, Mr. Davis has been a guarantor of the Company’s bank debt, for which he has received common stock as consideration. The Reporting Person’s interest in the securities of the issuer reported in Item 5 of this Schedule 13D includes common stock received as consideration of Mr. Davis’ guarantee of the Issuer’s bank debt through October 31, 2012; there is no agreement as to consideration for future guarantee periods should the bank debt not be retired by that date.

Item 5. Interest in Securities of the Issuer:

Item 5 has been amended and restated, in its entirety, to read:

(a) As of the close of business on April 9, 2012, the Reporting Persons beneficially owned 4,168,304 Shares, constituting approximately 22.7% of the outstanding Shares of the Issuer. Each of Mr. Davis, Davis Associates and the Davis 401K may be deemed to be a beneficial owner of all of these Shares for purposes of filing this Schedule 13D; however, each Reporting Person disclaims beneficial ownership in such shares, except to the extent of its own pecuniary interest therein.

The aggregate percentage of Shares beneficially owned by the Reporting Persons is based upon 16,964,231 Shares outstanding, which is the total number of Shares outstanding as of March 31, 2012, according to the transfer agent of the Issuer.

(b) By virtue of his direct and indirect control of Davis Associates and the Davis 401K, Mr. Davis is deemed to have sole voting and dispositive powers with respect to all of the Shares shown below.

(1) Includes 2,660,139 Shares owned by Mr. Davis and 1,181,523 Shares that could be acquired within 60 days of the date of filing of this Schedule 13D pursuant to the exercise of warrants or options or the conversion of convertible debt held by Mr. Davis. Also includes 205,978 Shares beneficially owned by the Davis 401K and 120,664 Shares beneficially owned by Davis Associates.

(2) Includes 63,182 shares currently available upon exercise of warrants.

(3) Includes 111,014 shares currently available upon exercise of warrants.

(c) Information concerning transactions in the Shares effected by the Reporting Persons during the past sixty days is set forth in Exhibit 99.1 hereto and is incorporated herein by reference.

(d) No person, other than the Reporting Persons, is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares.

(e) Not Applicable.

Item 7. Material to be Filed as Exhibits

Signature

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

EXHIBIT 99.1

The following table sets forth all acquisitions of common stock of the Issuer by the Reporting Persons during the sixty days preceding the filing of this Amendment No. 4 to Schedule 13D.