Holland Colours one of my errors of ommission

This is a graph of Holland Colours' stock price in blue and an average of 1,5 x book value and 15x earnings (Graham Number Value) in red. I have been following the company since 2013 but missed out on large gains in price and value by selling too soon.

“In the short run, the market is a voting machine but in the long run, it is a weighing machine.” - Benjamin Graham

At the end of 2013 I bought some Holland Colours stock for €28 per share and sold in February 2015 at €45 for a 60% profit. Much too early with 20/20 hindsight? Even now, Holland Colours seems like an acceptable investment for the Graham Defensive investor, although it is too small. 

SECTOR: [PASS]  Holland Colours is in manufacturing. Technology and financial stocks were considered too risky to invest in when this methodology was published. 

SALES: [FAIL] The investor must select companies of "adequate size". This includes companies with annual sales greater than €260 million.Holland Colours' sales of €91 million, based on 2018 sales, fails this test.

CURRENT RATIO:  [PASS] The current ratio must be greater than or equal to 2. Companies that meet this criterion are typically financially secure and defensive. Holland Colours' current ratio €36m/€12m of 3,0 easily passes this test.

LONG-TERM DEBT IN RELATION TO NET CURRENT ASSETS: [PASS] For industrial companies, long-term debt must not exceed net current assets (current assets minus current liabilities). Companies that do not meet this criterion lack the financial stability that this methodology likes to see. The long-term debt for Holland Colours is €0 million, while the net current assets are €24 million. Holland Colours passes this test easily.

LONG-TERM EPS GROWTH: [PASS] Companies must increase their EPS by at least 30% over a ten-year period and EPS must not have been negative for any year within the last 5 years. Companies with this type of growth tend to be financially secure and have proven themselves over time. Holland Colours' earnings have increased by 260% since 10 years ago.

Earnings Yield:  [PASS] The Earnings/Price (inverse P/E) %, based on the lesser of the current Earnings Yield or the Yield using average earnings over the last 3 fiscal years, must be "acceptable", which this methodology states is greater than 6,5%. Stocks with higher earnings yields are more defensive by nature. Holland Colours' E/P of 7% (using the average of the last 3 years Earnings) passes this test.

Graham Number value: [PASS] FAIL] The Price/Book ratio must also be reasonable. That is the Graham number value must be greater than the market price. Holland Colours has a Graham number = 

 √(15 x €7 EPS x 1,5 x €52 Book Value) = €102 

Dividend: €3.6/€111 = 3% 

Conclusion: Holland Colours has a strong balance sheet, is partly employee-owned and seems fairly priced for the Defensive Investor at a price of €110 in February 2020.