i2C RuntimeException

[Carlo Divita]

Hi guys, I have sometime this Runtime error:

java.lang.RuntimeException: Could not obtain an access-lock!
        at com.pi4j.io.i2c.impl.I2CBusImpl.runBusLockedDeviceAction(I2CBusImpl.java:275)
        at com.pi4j.io.i2c.impl.I2CBusImpl.writeByte(I2CBusImpl.java:185)
        at com.pi4j.io.i2c.impl.I2CDeviceImpl.write(I2CDeviceImpl.java:131)
        at com.pi4j.gpio.extension.mcp.MCP23017GpioProvider.setStateB(MCP23017GpioProvider.java:297)
        at com.pi4j.gpio.extension.mcp.MCP23017GpioProvider.setState(MCP23017GpioProvider.java:263)
        at com.pi4j.io.gpio.impl.GpioPinImpl.setState(GpioPinImpl.java:383)
        at com.pi4j.io.gpio.impl.GpioScheduledExecutorImpl.pulse(GpioScheduledExecutorImpl.java:120)
        at com.pi4j.io.gpio.impl.GpioPinImpl.pulse(GpioPinImpl.java:372)
        at com.pi4j.io.gpio.impl.GpioPinImpl.pulse(GpioPinImpl.java:325)
        at com.pi4j.io.gpio.impl.GpioPinImpl.pulse(GpioPinImpl.java:305)
        at com.pi4j.io.gpio.impl.GpioPinImpl.pulse(GpioPinImpl.java:265)

how can I solve this problem? it's very important for me to solve it.

thank you very much

Carlo